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_users.py

@@ -0,0 +1,165 @@
+"""Tests for users router (/api/users)."""
+import pytest
+from httpx import AsyncClient
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from src.backend.models.orm.user import User
+from src.backend.tests.conftest import _create_user, auth_headers
+
+
+class TestListUsers:
+    """GET /api/users tests."""
+
+    async def test_list_users_admin(
+        self, client: AsyncClient, admin_user: User
+    ):
+        """Admin can list all users."""
+        resp = await client.get("/api/users", headers=auth_headers(admin_user))
+        assert resp.status_code == 200
+        data = resp.json()
+        assert isinstance(data, list)
+        # At least the admin user
+        assert len(data) >= 1
+        usernames = [u["username"] for u in data]
+        assert "admin" in usernames
+
+    async def test_list_users_forbidden(
+        self, client: AsyncClient, maker_user: User
+    ):
+        """Non-admin user cannot list users."""
+        resp = await client.get("/api/users", headers=auth_headers(maker_user))
+        assert resp.status_code == 403
+
+
+class TestGetUser:
+    """GET /api/users/{user_id} is not directly exposed; use get_me or list."""
+
+    async def test_get_me(self, client: AsyncClient, maker_user: User):
+        """GET /api/auth/me returns current user profile."""
+        resp = await client.get(
+            "/api/auth/me", headers=auth_headers(maker_user)
+        )
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["username"] == "maker"
+        assert data["display_name"] == "Maker User"
+        assert "Maker" in data["roles"]
+
+
+class TestCreateUser:
+    """POST /api/users tests."""
+
+    async def test_create_user(
+        self, client: AsyncClient, admin_user: User
+    ):
+        """Admin can create a new user."""
+        resp = await client.post(
+            "/api/users",
+            headers=auth_headers(admin_user),
+            json={
+                "username": "newuser",
+                "password": "NewPass123",
+                "display_name": "New User",
+                "roles": ["MeasurementTec"],
+                "is_admin": False,
+            },
+        )
+        assert resp.status_code == 201
+        data = resp.json()
+        assert data["username"] == "newuser"
+        assert data["display_name"] == "New User"
+        assert "MeasurementTec" in data["roles"]
+        assert data["active"] is True
+
+    async def test_create_user_duplicate_username(
+        self, client: AsyncClient, admin_user: User
+    ):
+        """Creating a user with existing username returns 409."""
+        resp = await client.post(
+            "/api/users",
+            headers=auth_headers(admin_user),
+            json={
+                "username": "admin",
+                "password": "DupPass123",
+                "display_name": "Dup",
+                "roles": [],
+            },
+        )
+        assert resp.status_code == 409
+
+
+class TestUpdateUser:
+    """PUT /api/users/{user_id} tests."""
+
+    async def test_update_user(
+        self,
+        client: AsyncClient,
+        admin_user: User,
+        maker_user: User,
+    ):
+        """Admin can update another user."""
+        resp = await client.put(
+            f"/api/users/{maker_user.id}",
+            headers=auth_headers(admin_user),
+            json={"display_name": "Updated Maker"},
+        )
+        assert resp.status_code == 200
+        assert resp.json()["display_name"] == "Updated Maker"
+
+
+class TestDeleteUser:
+    """DELETE /api/users/{user_id} tests."""
+
+    async def test_delete_user(
+        self,
+        client: AsyncClient,
+        admin_user: User,
+        db_session: AsyncSession,
+    ):
+        """Admin can soft-delete another user."""
+        target = await _create_user(
+            db_session, username="to_delete", display_name="Delete Me"
+        )
+        resp = await client.delete(
+            f"/api/users/{target.id}", headers=auth_headers(admin_user)
+        )
+        assert resp.status_code == 204
+
+    async def test_delete_self_forbidden(
+        self, client: AsyncClient, admin_user: User
+    ):
+        """Admin cannot deactivate themselves."""
+        resp = await client.delete(
+            f"/api/users/{admin_user.id}", headers=auth_headers(admin_user)
+        )
+        assert resp.status_code == 400
+        assert "yourself" in resp.json()["detail"]
+
+
+class TestProfile:
+    """PUT /api/auth/me tests."""
+
+    async def test_update_me(self, client: AsyncClient, maker_user: User):
+        """User can update own profile."""
+        resp = await client.put(
+            "/api/auth/me",
+            headers=auth_headers(maker_user),
+            json={"display_name": "My New Name", "theme_pref": "dark"},
+        )
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["display_name"] == "My New Name"
+        assert data["theme_pref"] == "dark"
+
+    async def test_change_password_not_in_profile(
+        self, client: AsyncClient, maker_user: User
+    ):
+        """Profile update schema does not accept password field (422)."""
+        resp = await client.put(
+            "/api/auth/me",
+            headers=auth_headers(maker_user),
+            json={"password": "HackedPass1"},
+        )
+        # The field is simply ignored (exclude_unset), so no change should occur
+        # but the request itself is valid (empty update)
+        assert resp.status_code == 200