Add listing decisions (like/dislike) backend with detail endpoint

- ListingDecision model with unique constraint on (user_id, listing_id, listing_type)
- Alembic migration for listingdecision table
- DecisionRepository with dialect-aware upsert (MySQL/SQLite)
- DecisionService with input validation
- Decision API routes: PUT/GET/DELETE on /api/decisions
- GET /api/listing/{id}/detail endpoint extracting full property info from additional_info
- Add listing ID to GeoJSON feature properties
- Decision filtering on GeoJSON stream endpoint (decision_filter param)

models/decision.py

@@ -1,13 +1,20 @@
-from datetime import datetime, UTC
+from datetime import datetime
 
-from sqlmodel import SQLModel, Field
+from sqlmodel import SQLModel, Field, UniqueConstraint
 
 
 class ListingDecision(SQLModel, table=True):
+    __table_args__ = (
+        UniqueConstraint(
+            'user_id', 'listing_id', 'listing_type',
+            name='uq_decision_user_listing_type',
+        ),
+    )
+
     id: int | None = Field(default=None, primary_key=True)
     user_id: int = Field(nullable=False, foreign_key="user.id", index=True)
     listing_id: int = Field(nullable=False, index=True)
     listing_type: str = Field(nullable=False)  # "RENT" or "BUY"
-    decision: str = Field(nullable=False)  # "liked" or "disliked"
-    created_at: datetime = Field(default_factory=lambda: datetime.now(UTC))
-    updated_at: datetime = Field(default_factory=lambda: datetime.now(UTC))
+    decision: str = Field(nullable=False)       # "liked" or "disliked"
+    created_at: datetime = Field(default_factory=datetime.utcnow)
+    updated_at: datetime = Field(default_factory=datetime.utcnow)