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/routers/settings.py

@@ -0,0 +1,153 @@
+"""System settings router - read/update settings, upload company logo."""
+from pathlib import Path
+
+from fastapi import APIRouter, Depends, File, HTTPException, UploadFile, status
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from src.backend.config import settings
+from src.backend.database import get_db
+from src.backend.api.middleware.api_key import get_current_user, require_admin_user
+from src.backend.models.orm.setting import SystemSetting
+from src.backend.models.orm.user import User
+
+router = APIRouter(prefix="/api/settings", tags=["settings"])
+
+
+@router.get("/")
+async def get_settings(
+    user: User = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Get all system settings as a dictionary.
+
+    Returns key-value pairs of all settings.
+    Available to all authenticated users.
+    """
+    result = await db.execute(select(SystemSetting))
+    settings_list = result.scalars().all()
+
+    settings_dict = {
+        setting.setting_key: setting.setting_value
+        for setting in settings_list
+    }
+
+    return settings_dict
+
+
+@router.put("/")
+async def update_settings(
+    settings_data: dict[str, str],
+    user: User = Depends(require_admin_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Update multiple system settings.
+
+    Expects a JSON object with setting_key: setting_value pairs.
+    Only admins can update settings.
+    """
+    updated_keys = []
+
+    for key, value in settings_data.items():
+        # Check if setting exists
+        result = await db.execute(
+            select(SystemSetting).where(SystemSetting.setting_key == key)
+        )
+        setting = result.scalar_one_or_none()
+
+        if setting is None:
+            # Create new setting (assume type 'string' for new settings)
+            setting = SystemSetting(
+                setting_key=key,
+                setting_value=value,
+                setting_type="string",
+                updated_by=user.id,
+            )
+            db.add(setting)
+        else:
+            # Update existing setting
+            setting.setting_value = value
+            setting.updated_by = user.id
+
+        updated_keys.append(key)
+
+    await db.flush()
+
+    return {
+        "message": f"Updated {len(updated_keys)} settings",
+        "updated_keys": updated_keys,
+    }
+
+
+@router.post("/logo")
+async def upload_company_logo(
+    file: UploadFile = File(...),
+    user: User = Depends(require_admin_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Upload company logo.
+
+    Saves logo to uploads/logos/ and updates company_logo_path setting.
+    Only admins can upload the logo.
+    """
+    # Validate file type (must be image)
+    allowed_types = {"image/jpeg", "image/png", "image/gif", "image/webp", "image/svg+xml"}
+    if file.content_type not in allowed_types:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail=f"File type {file.content_type} not allowed. Must be an image.",
+        )
+
+    # Read file content
+    content = await file.read()
+    file_size = len(content)
+
+    # Validate file size
+    max_bytes = settings.max_upload_size_mb * 1024 * 1024
+    if file_size > max_bytes:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail=f"File size {file_size} bytes exceeds maximum {settings.max_upload_size_mb}MB",
+        )
+
+    # Create logos directory
+    logos_dir = settings.upload_path / "logos"
+    logos_dir.mkdir(parents=True, exist_ok=True)
+
+    # Use a fixed filename for the company logo
+    file_extension = Path(file.filename).suffix
+    logo_filename = f"company_logo{file_extension}"
+    logo_path = logos_dir / logo_filename
+
+    # Write file
+    logo_path.write_bytes(content)
+
+    # Update setting in database
+    relative_path = logo_path.relative_to(settings.upload_path)
+    logo_path_str = str(relative_path).replace("\\", "/")
+
+    result = await db.execute(
+        select(SystemSetting).where(SystemSetting.setting_key == "company_logo_path")
+    )
+    setting = result.scalar_one_or_none()
+
+    if setting is None:
+        setting = SystemSetting(
+            setting_key="company_logo_path",
+            setting_value=logo_path_str,
+            setting_type="string",
+            description="Path to company logo file",
+            updated_by=user.id,
+        )
+        db.add(setting)
+    else:
+        setting.setting_value = logo_path_str
+        setting.updated_by = user.id
+
+    await db.flush()
+
+    return {
+        "message": "Company logo uploaded successfully",
+        "logo_path": logo_path_str,
+        "file_size": file_size,
+    }