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/frontend/flask_app/tests/test_measure.py

@@ -0,0 +1,94 @@
+"""Tests for measure blueprint (client/blueprints/measure.py).
+
+Covers recipe selection, task list, login requirement, and measurement submission.
+"""
+import pytest
+
+
+class TestSelectRecipe:
+    """GET /measure/select tests."""
+
+    def test_select_recipe_renders(self, logged_in_client, mock_api_client, monkeypatch):
+        """Recipe selection page renders for MeasurementTec role."""
+        monkeypatch.setenv("STATION_CODE", "ST-TEST")
+        import config
+        import importlib
+        importlib.reload(config)
+        import blueprints.measure
+        importlib.reload(blueprints.measure)
+
+        mock_api_client.get_station_recipes.return_value = [
+            {"id": 1, "code": "REC-001", "name": "Test Recipe"},
+        ]
+
+        resp = logged_in_client.get("/measure/select")
+        assert resp.status_code == 200
+
+    def test_select_recipe_requires_login(self, client):
+        """Unauthenticated user is redirected to login."""
+        resp = client.get("/measure/select", follow_redirects=False)
+        assert resp.status_code == 302
+        assert "/auth/login" in resp.headers["Location"]
+
+
+class TestTaskList:
+    """GET /measure/tasks/<recipe_id> tests."""
+
+    def test_task_list_renders(self, logged_in_client, mock_api_client):
+        """Task list page renders with recipe and task data."""
+        # First call: recipe details (dict), second call: tasks list.
+        # The route calls tasks_resp.get("error") so the mock must return
+        # a dict (not a bare list) to avoid AttributeError.
+        mock_api_client.get.side_effect = [
+            {"id": 1, "code": "REC-001", "name": "Test Recipe"},
+            {
+                "items": [
+                    {"id": 1, "title": "Task 1", "order_index": 0},
+                    {"id": 2, "title": "Task 2", "order_index": 1},
+                ],
+            },
+        ]
+
+        resp = logged_in_client.get("/measure/tasks/1")
+        assert resp.status_code == 200
+
+
+class TestSaveMeasurement:
+    """POST /measure/save-measurement tests."""
+
+    def test_save_measurement_proxy(self, logged_in_client, mock_api_client):
+        """Save measurement forwards data to API and returns 201."""
+        mock_api_client.post.return_value = {
+            "id": 1,
+            "subtask_id": 10,
+            "task_id": 5,
+            "value": 9.95,
+            "pass_fail": "pass",
+        }
+
+        resp = logged_in_client.post(
+            "/measure/save-measurement",
+            json={
+                "subtask_id": 10,
+                "task_id": 5,
+                "value": 9.95,
+                "pass_fail": "pass",
+                "deviation": 0.05,
+            },
+            content_type="application/json",
+        )
+        assert resp.status_code == 201
+        data = resp.get_json()
+        assert data["id"] == 1
+        assert data["pass_fail"] == "pass"
+
+    def test_save_measurement_missing_fields(self, logged_in_client, mock_api_client):
+        """Missing required fields return 400."""
+        resp = logged_in_client.post(
+            "/measure/save-measurement",
+            json={"subtask_id": 10},  # missing task_id and value
+            content_type="application/json",
+        )
+        assert resp.status_code == 400
+        data = resp.get_json()
+        assert data["error"] is True