chore(v2): restructure monorepo to src/ layout with uv

Aligns the repo with the python-project-spec-design.md template chosen
for V2.0.0. Big move, no logic changes. The 3 pre-existing test
failures (test_recipes::test_update_recipe, test_recipes::
test_recipe_versioning, test_tasks::test_reorder_tasks, plus the
client test_save_measurement_proxy) survive unchanged.

Layout changes
- server/        -> src/backend/
- server/middleware/ -> src/backend/api/middleware/
- server/routers/    -> src/backend/api/routers/
- server/models/     -> src/backend/models/orm/
- server/schemas/    -> src/backend/models/api/
- server/uploads/    -> uploads/ (project root, mounted volume)
- server/tests/      -> src/backend/tests/
- client/            -> src/frontend/flask_app/ (Flask kept; React
  deroga is documented in CLAUDE.md, justified by tablet UX, USB
  caliper/barcode workflow and Fabric.js integration)

Tooling
- pyproject.toml: monorepo with [project] core deps and
  optional-dependencies server / client / dev. Replaces both
  server/requirements.txt and client/requirements.txt.
- uv.lock + .python-version (3.11) committed for reproducible builds.
- Dockerfile (root, backend) and Dockerfile.frontend rewritten to use
  uv sync --frozen --no-dev --extra server|client; legacy Dockerfiles
  preserved as Dockerfile.legacy for reference but excluded from build
  context via .dockerignore.
- docker-compose.dev.yml + docker-compose.yml: build context now ".",
  dockerfile pointing to the root files.

Code adjustments forced by the move
- Every "from config|database|models|schemas|services|routers|middleware
  import ..." rewritten to its src.backend.* equivalent (50+ files
  including indented inline imports inside test bodies).
- src/backend/migrations/env.py: insert project root into sys.path so
  alembic can resolve src.backend.* imports regardless of cwd.
- src/backend/config.py: env_file ../../.env (was ../.env), upload_path
  resolves project root via parents[2].
- src/backend/tests/conftest.py + tests: import ... from src.backend.*
  instead of bare names; old per-directory pytest.ini files removed in
  favor of root pyproject.toml [tool.pytest.ini_options].
- .gitignore: uploads/ at root, src/frontend/flask_app/static/css/
  tailwind.css path; .dockerignore tightened.
- CLAUDE.md: rewrote sections "Layout del repository", "Comandi di
  Sviluppo", "Database & Migrations", "Test", "i18n", and all path
  references throughout the architecture sections.

Verified
- uv lock resolves 77 packages; uv sync --extra server --extra client
  --extra dev installs cleanly.
- uv run pytest: 171 passed, 4 pre-existing failures.
- uv run alembic -c src/backend/migrations/alembic.ini check loads
  config and metadata (errors only on the absent local MySQL).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/backend/tests/test_stations_api.py

@@ -0,0 +1,203 @@
+"""Integration tests for /api/stations endpoints."""
+import pytest
+from httpx import AsyncClient
+
+from src.backend.tests.conftest import auth_headers, create_test_recipe
+
+
+async def test_list_stations_requires_auth(client: AsyncClient):
+    resp = await client.get("/api/stations")
+    assert resp.status_code == 401
+
+
+async def test_create_station_as_admin(client: AsyncClient, admin_user):
+    resp = await client.post(
+        "/api/stations",
+        headers=auth_headers(admin_user),
+        json={"code": "ST-API", "name": "Via API"},
+    )
+    assert resp.status_code == 201, resp.text
+    body = resp.json()
+    assert body["code"] == "ST-API"
+    assert body["active"] is True
+    assert body["id"] > 0
+
+
+async def test_create_station_non_admin_is_403(client: AsyncClient, maker_user):
+    resp = await client.post(
+        "/api/stations",
+        headers=auth_headers(maker_user),
+        json={"code": "ST-NO", "name": "No"},
+    )
+    assert resp.status_code == 403
+
+
+async def test_update_station(client: AsyncClient, admin_user):
+    created = await client.post(
+        "/api/stations",
+        headers=auth_headers(admin_user),
+        json={"code": "ST-UP", "name": "Old"},
+    )
+    station_id = created.json()["id"]
+    resp = await client.put(
+        f"/api/stations/{station_id}",
+        headers=auth_headers(admin_user),
+        json={"name": "New", "active": False},
+    )
+    assert resp.status_code == 200
+    body = resp.json()
+    assert body["name"] == "New"
+    assert body["active"] is False
+
+
+async def test_delete_station(client: AsyncClient, admin_user):
+    created = await client.post(
+        "/api/stations",
+        headers=auth_headers(admin_user),
+        json={"code": "ST-D", "name": "D"},
+    )
+    sid = created.json()["id"]
+    resp = await client.delete(
+        f"/api/stations/{sid}", headers=auth_headers(admin_user),
+    )
+    assert resp.status_code == 204
+    again = await client.get(
+        f"/api/stations/{sid}", headers=auth_headers(admin_user),
+    )
+    assert again.status_code == 404
+
+
+async def test_assign_and_unassign_recipe(
+    client: AsyncClient, admin_user, db_session,
+):
+    recipe = await create_test_recipe(db_session, user_id=admin_user.id, code="REC-AS")
+    await db_session.commit()
+    created = await client.post(
+        "/api/stations",
+        headers=auth_headers(admin_user),
+        json={"code": "ST-ASSIGN", "name": "A"},
+    )
+    sid = created.json()["id"]
+    a = await client.post(
+        f"/api/stations/{sid}/recipes",
+        headers=auth_headers(admin_user),
+        json={"recipe_id": recipe.id},
+    )
+    assert a.status_code == 201
+    r = await client.get(
+        f"/api/stations/{sid}/recipes",
+        headers=auth_headers(admin_user),
+    )
+    assert r.status_code == 200
+    assert [rec["code"] for rec in r.json()] == ["REC-AS"]
+    u = await client.delete(
+        f"/api/stations/{sid}/recipes/{recipe.id}",
+        headers=auth_headers(admin_user),
+    )
+    assert u.status_code == 204
+    r2 = await client.get(
+        f"/api/stations/{sid}/recipes",
+        headers=auth_headers(admin_user),
+    )
+    assert r2.json() == []
+
+
+async def test_list_recipes_by_station_code(
+    client: AsyncClient, admin_user, measurement_tec_user, db_session,
+):
+    recipe = await create_test_recipe(db_session, user_id=admin_user.id, code="REC-BC")
+    await db_session.commit()
+    created = await client.post(
+        "/api/stations",
+        headers=auth_headers(admin_user),
+        json={"code": "ST-BC", "name": "BC"},
+    )
+    sid = created.json()["id"]
+    await client.post(
+        f"/api/stations/{sid}/recipes",
+        headers=auth_headers(admin_user),
+        json={"recipe_id": recipe.id},
+    )
+    resp = await client.get(
+        "/api/stations/by-code/ST-BC/recipes",
+        headers=auth_headers(measurement_tec_user),
+    )
+    assert resp.status_code == 200
+    assert [r["code"] for r in resp.json()] == ["REC-BC"]
+
+
+async def test_list_recipes_by_unknown_code_404(
+    client: AsyncClient, measurement_tec_user,
+):
+    resp = await client.get(
+        "/api/stations/by-code/ST-DOES-NOT-EXIST/recipes",
+        headers=auth_headers(measurement_tec_user),
+    )
+    assert resp.status_code == 404
+
+
+async def test_admin_can_list_stations(client: AsyncClient, admin_user):
+    await client.post(
+        "/api/stations",
+        headers=auth_headers(admin_user),
+        json={"code": "ST-L1", "name": "A"},
+    )
+    await client.post(
+        "/api/stations",
+        headers=auth_headers(admin_user),
+        json={"code": "ST-L2", "name": "B", "active": False},
+    )
+    resp = await client.get("/api/stations", headers=auth_headers(admin_user))
+    assert resp.status_code == 200
+    codes = {s["code"] for s in resp.json()}
+    assert {"ST-L1", "ST-L2"}.issubset(codes)
+
+    resp_active = await client.get(
+        "/api/stations?active_only=true", headers=auth_headers(admin_user),
+    )
+    assert resp_active.status_code == 200
+    active_codes = {s["code"] for s in resp_active.json()}
+    assert "ST-L1" in active_codes
+    assert "ST-L2" not in active_codes
+
+
+async def test_assign_recipe_not_found_returns_404(
+    client: AsyncClient, admin_user,
+):
+    created = await client.post(
+        "/api/stations",
+        headers=auth_headers(admin_user),
+        json={"code": "ST-NR", "name": "NR"},
+    )
+    sid = created.json()["id"]
+    resp = await client.post(
+        f"/api/stations/{sid}/recipes",
+        headers=auth_headers(admin_user),
+        json={"recipe_id": 99999},
+    )
+    assert resp.status_code == 404
+
+
+async def test_duplicate_assignment_returns_409(
+    client: AsyncClient, admin_user, db_session,
+):
+    recipe = await create_test_recipe(db_session, user_id=admin_user.id, code="REC-DUP")
+    await db_session.commit()
+    created = await client.post(
+        "/api/stations",
+        headers=auth_headers(admin_user),
+        json={"code": "ST-DUP-A", "name": "Dup"},
+    )
+    sid = created.json()["id"]
+    first = await client.post(
+        f"/api/stations/{sid}/recipes",
+        headers=auth_headers(admin_user),
+        json={"recipe_id": recipe.id},
+    )
+    assert first.status_code == 201
+    second = await client.post(
+        f"/api/stations/{sid}/recipes",
+        headers=auth_headers(admin_user),
+        json={"recipe_id": recipe.id},
+    )
+    assert second.status_code == 409