Worker di visione per stazione: modello, API, migrazione 019, execute_task (#45)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NABedeMX43pyXZbDNUgA5B

src/backend/models/api/station.py

@@ -2,7 +2,19 @@
 from src.backend.models.api.tipi import UtcDateTime
 from typing import Optional
 
-from pydantic import BaseModel, ConfigDict, Field
+from pydantic import BaseModel, ConfigDict, Field, field_validator
+
+
+def _normalize_worker_url(value: Optional[str]) -> Optional[str]:
+    """Vuoto/spazi -> None (worker centrale); altrimenti http(s) senza '/' finale (#45)."""
+    if value is None:
+        return None
+    value = value.strip()
+    if not value:
+        return None
+    if not value.lower().startswith(("http://", "https://")):
+        raise ValueError("vision_worker_url must start with http:// or https://")
+    return value.rstrip("/")
 
 
 class StationCreate(BaseModel):
@@ -11,6 +23,10 @@ class StationCreate(BaseModel):
     location: Optional[str] = Field(default=None, max_length=255)
     notes: Optional[str] = None
     active: bool = True
+    # worker di visione della stazione (#45); vuoto = centrale
+    vision_worker_url: Optional[str] = Field(default=None, max_length=500)
+
+    _check_worker_url = field_validator("vision_worker_url")(_normalize_worker_url)
 
 
 class StationUpdate(BaseModel):
@@ -18,6 +34,10 @@ class StationUpdate(BaseModel):
     location: Optional[str] = Field(default=None, max_length=255)
     notes: Optional[str] = None
     active: Optional[bool] = None
+    # worker di visione della stazione (#45); "" -> None riporta al centrale
+    vision_worker_url: Optional[str] = Field(default=None, max_length=500)
+
+    _check_worker_url = field_validator("vision_worker_url")(_normalize_worker_url)
 
 
 class StationResponse(BaseModel):
@@ -28,6 +48,7 @@ class StationResponse(BaseModel):
     location: Optional[str]
     notes: Optional[str]
     active: bool
+    vision_worker_url: Optional[str] = None  # #45
     created_by: int
     created_at: UtcDateTime