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/recipe.py

@@ -0,0 +1,65 @@
+"""Pydantic schemas for Recipe and RecipeVersion operations."""
+from datetime import datetime
+from typing import Optional, TYPE_CHECKING
+
+from pydantic import BaseModel, ConfigDict, Field
+
+if TYPE_CHECKING:
+    from schemas.task import TaskResponse
+
+
+class RecipeCreate(BaseModel):
+    """Schema for creating a new recipe."""
+    code: str = Field(..., min_length=1, max_length=100)
+    name: str = Field(..., min_length=1, max_length=255)
+    description: Optional[str] = None
+
+
+class RecipeUpdate(BaseModel):
+    """Schema for updating a recipe (creates new version)."""
+    name: Optional[str] = Field(None, min_length=1, max_length=255)
+    description: Optional[str] = None
+    change_notes: Optional[str] = None
+
+
+class RecipeVersionResponse(BaseModel):
+    """Schema for recipe version response."""
+    model_config = ConfigDict(from_attributes=True)
+
+    id: int
+    recipe_id: int
+    version_number: int
+    is_current: bool
+    created_by: int
+    created_at: datetime
+    change_notes: Optional[str] = None
+    tasks: list["TaskResponse"] = []
+
+
+class RecipeResponse(BaseModel):
+    """Schema for recipe response."""
+    model_config = ConfigDict(from_attributes=True)
+
+    id: int
+    code: str
+    name: str
+    description: Optional[str] = None
+    created_by: int
+    created_at: datetime
+    active: bool
+    current_version: Optional[RecipeVersionResponse] = None
+
+
+class RecipeListResponse(BaseModel):
+    """Schema for paginated recipe list."""
+    items: list[RecipeResponse]
+    total: int
+    page: int
+    per_page: int
+    pages: int
+
+
+# Forward reference imports for model_rebuild
+from schemas.task import TaskResponse  # noqa: E402
+RecipeVersionResponse.model_rebuild()
+RecipeResponse.model_rebuild()