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>

pyproject.toml

@@ -0,0 +1,73 @@
+[project]
+name = "tiemeasureflow"
+version = "2.0.0"
+description = "TieMeasureFlow by Tielogic — manual caliper measurement task management for industrial QA stations."
+requires-python = ">=3.11"
+authors = [
+    { name = "Adriano Dal Pastro", email = "adrianodalpastro@tielogic.com" },
+]
+
+# Shared core deps used by both backend and the Flask frontend.
+dependencies = [
+    "pydantic>=2.0.0",
+    "pydantic-settings>=2.0.0",
+    "python-dotenv>=1.0.0",
+]
+
+[project.optional-dependencies]
+
+# Backend (FastAPI + DB + reports).
+server = [
+    "fastapi>=0.110.0",
+    "uvicorn[standard]>=0.30.0",
+    "sqlalchemy[asyncio]>=2.0.0",
+    "asyncmy>=0.2.0",
+    "alembic>=1.13.0",
+    "bcrypt>=4.0.0",
+    "pillow>=10.0.0",
+    "python-multipart>=0.0.6",
+    "jinja2>=3.1.0",
+    "plotly>=5.0.0",
+    "kaleido>=0.2.0",
+    "weasyprint>=62.0",
+]
+
+# Frontend (Flask tablet UI).
+client = [
+    "flask>=3.0.0",
+    "flask-babel>=4.0.0",
+    "flask-wtf>=1.2.0",
+    "requests>=2.31.0",
+    "urllib3>=2.0.0",
+    "gunicorn>=21.0.0",
+]
+
+# Dev / test (covers both server and client tests).
+dev = [
+    "pytest>=8.0.0",
+    "pytest-asyncio>=0.23.0",
+    "httpx>=0.27.0",
+    "aiosqlite>=0.20.0",
+    "coverage>=7.0.0",
+]
+
+[project.scripts]
+# Backend
+server = "uvicorn:run"  # placeholder, real CMD lives in Dockerfile
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[tool.hatch.build.targets.wheel]
+# Source layout will be src/backend/ and src/frontend/flask_app/ after the
+# folder restructure (Phase 2 of the V2.0.0 plan).
+packages = ["src/backend", "src/frontend"]
+
+[tool.uv]
+# Pin the resolver to the deps we declared; reproducible builds.
+package = false
+
+[tool.pytest.ini_options]
+asyncio_mode = "auto"
+testpaths = ["src/backend/tests", "src/frontend/flask_app/tests"]