feat: FASE 1 - Backend Core (modelli, auth, API)

Implementazione completa del backend FastAPI:
- Modelli SQLAlchemy: User, Recipe, RecipeVersion, RecipeTask,
  RecipeSubtask, Measurement, AccessLog, SystemSetting, RecipeVersionAudit
- Schemas Pydantic v2 per tutti i CRUD + statistiche SPC
- Middleware: API Key auth (X-API-Key) con role checking + access logging
- Router: auth, users, recipes, tasks, measurements, files, settings
- Services: auth (bcrypt+secrets), recipe (copy-on-write versioning),
  measurement (auto pass/fail con UTL/UWL/LWL/LTL)
- Alembic env.py con import modelli attivi
- Fix architect review: no double-commit, recipe_id subquery filter,
  user_id in access logs, type annotations corrette

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/schemas/measurement.py

@@ -0,0 +1,62 @@
+"""Pydantic schemas for Measurement operations."""
+from datetime import datetime
+from typing import Optional
+
+from pydantic import BaseModel, ConfigDict, Field
+
+
+class MeasurementCreate(BaseModel):
+    """Schema for creating a single measurement."""
+    subtask_id: int
+    version_id: int
+    value: float
+    lot_number: Optional[str] = Field(None, max_length=100)
+    serial_number: Optional[str] = Field(None, max_length=100)
+    input_method: str = Field("manual", pattern="^(usb_caliper|manual)$")
+
+
+class MeasurementBatchCreate(BaseModel):
+    """Schema for creating multiple measurements at once."""
+    measurements: list[MeasurementCreate]
+
+
+class MeasurementResponse(BaseModel):
+    """Schema for measurement response."""
+    model_config = ConfigDict(from_attributes=True)
+
+    id: int
+    subtask_id: int
+    version_id: int
+    measured_by: int
+    value: float
+    pass_fail: str
+    deviation: Optional[float] = None
+    lot_number: Optional[str] = None
+    serial_number: Optional[str] = None
+    input_method: str
+    measured_at: datetime
+    synced_to_csv: bool
+
+
+class MeasurementListResponse(BaseModel):
+    """Schema for paginated measurement list."""
+    items: list[MeasurementResponse]
+    total: int
+    page: int
+    per_page: int
+    pages: int
+
+
+class MeasurementQuery(BaseModel):
+    """Schema for measurement query filters."""
+    recipe_id: Optional[int] = None
+    version_id: Optional[int] = None
+    subtask_id: Optional[int] = None
+    measured_by: Optional[int] = None
+    lot_number: Optional[str] = None
+    serial_number: Optional[str] = None
+    date_from: Optional[datetime] = None
+    date_to: Optional[datetime] = None
+    pass_fail: Optional[str] = Field(None, pattern="^(pass|warning|fail)$")
+    page: int = Field(1, ge=1)
+    per_page: int = Field(50, ge=1, le=500)