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/api/middleware/logging.py

@@ -0,0 +1,54 @@
+"""Access logging middleware for FastAPI."""
+import time
+from typing import Callable
+
+from fastapi import Request, Response
+from starlette.middleware.base import BaseHTTPMiddleware
+from sqlalchemy import insert
+
+from src.backend.database import async_session_factory
+from src.backend.models.orm.access_log import AccessLog
+
+
+class AccessLogMiddleware(BaseHTTPMiddleware):
+    """Middleware that logs every API request to the access_logs table."""
+
+    # Paths to exclude from logging (health checks, static files)
+    EXCLUDED_PATHS = {"/api/health", "/docs", "/openapi.json", "/redoc"}
+
+    async def dispatch(self, request: Request, call_next: Callable) -> Response:
+        # Skip excluded paths
+        if request.url.path in self.EXCLUDED_PATHS:
+            return await call_next(request)
+
+        start_time = time.time()
+        response = await call_next(request)
+        duration_ms = (time.time() - start_time) * 1000
+
+        # Extract user info from request state (set by auth middleware)
+        user_id = getattr(request.state, "user_id", None)
+
+        # Log asynchronously (don't block response)
+        try:
+            async with async_session_factory() as session:
+                await session.execute(
+                    insert(AccessLog).values(
+                        user_id=user_id,
+                        action=f"{request.method} {request.url.path}",
+                        details={
+                            "method": request.method,
+                            "path": request.url.path,
+                            "query": str(request.query_params),
+                            "status_code": response.status_code,
+                            "duration_ms": round(duration_ms, 2),
+                        },
+                        ip_address=request.client.host if request.client else None,
+                        user_agent=request.headers.get("user-agent", "")[:500],
+                    )
+                )
+                await session.commit()
+        except Exception:
+            # Don't fail the request if logging fails
+            pass
+
+        return response