Add FastAPI backend with PostGIS-backed nearby search

FastAPI service backed by PostgreSQL+PostGIS: cities/places/place_content
schema (normalized per-language, per-length content for easy future
re-ingestion), Alembic migration, an iterative-radius-expansion nearby
search endpoint, a name-search fallback for denied-location flows, and
a YAML seed loader CLI. Verified end-to-end against a live Docker
Postgres+PostGIS instance (migration, city seed, place/content CRUD,
and nearby radius expansion all confirmed working via curl).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/app/api/routes/places.py

@@ -0,0 +1,117 @@
+from fastapi import APIRouter, Depends, HTTPException, Query
+from geoalchemy2 import Geometry
+from sqlalchemy import and_, cast, func, select
+from sqlalchemy.orm import Session
+
+from app.api.deps import lang_param, length_param
+from app.db.session import get_db
+from app.models.city import City
+from app.models.enums import PlaceCategory
+from app.models.place import Place
+from app.models.place_content import PlaceContent
+from app.schemas.common import LatLon
+from app.schemas.place import ContentOut, PlaceDetail, PlaceListItem
+from app.services.geocoding import search_places
+
+router = APIRouter(tags=["places"])
+
+
+@router.get("/places/search", response_model=list[PlaceListItem])
+def search(
+    q: str = Query(min_length=1),
+    city_slug: str | None = Query(default=None),
+    lang: str = Depends(lang_param),
+    db: Session = Depends(get_db),
+) -> list[PlaceListItem]:
+    rows = search_places(db, q=q, language=lang, city_slug=city_slug)
+    return [
+        PlaceListItem(id=place.id, slug=place.slug, category=place.category, name=content.title, location=LatLon(lat=lat, lon=lon))
+        for place, content, lon, lat in rows
+    ]
+
+
+@router.get("/places/{place_id}", response_model=PlaceDetail)
+def get_place(
+    place_id: int,
+    lang: str = Depends(lang_param),
+    length: str = Depends(length_param),
+    db: Session = Depends(get_db),
+) -> PlaceDetail:
+    stmt = (
+        select(
+            Place,
+            PlaceContent,
+            func.ST_X(cast(Place.location, Geometry)).label("lon"),
+            func.ST_Y(cast(Place.location, Geometry)).label("lat"),
+        )
+        .join(
+            PlaceContent,
+            and_(
+                PlaceContent.place_id == Place.id,
+                PlaceContent.language == lang,
+                PlaceContent.length == length,
+            ),
+        )
+        .where(Place.id == place_id)
+    )
+    row = db.execute(stmt).first()
+    if row is None:
+        raise HTTPException(status_code=404, detail="Place not found")
+
+    place, content, lon, lat = row
+    return PlaceDetail(
+        id=place.id,
+        slug=place.slug,
+        category=place.category,
+        location=LatLon(lat=lat, lon=lon),
+        address=place.address,
+        district=place.district,
+        built_year=place.built_year,
+        architect_builder=place.architect_builder,
+        architectural_style=place.architectural_style,
+        content=ContentOut(language=content.language, length=content.length, title=content.title, body=content.body),
+    )
+
+
+@router.get("/cities/{city_slug}/places", response_model=list[PlaceListItem])
+def list_city_places(
+    city_slug: str,
+    category: PlaceCategory | None = Query(default=None),
+    district: str | None = Query(default=None),
+    q: str | None = Query(default=None),
+    lang: str = Depends(lang_param),
+    db: Session = Depends(get_db),
+) -> list[PlaceListItem]:
+    city = db.scalar(select(City).where(City.slug == city_slug))
+    if city is None:
+        raise HTTPException(status_code=404, detail="City not found")
+
+    stmt = (
+        select(
+            Place,
+            PlaceContent,
+            func.ST_X(cast(Place.location, Geometry)).label("lon"),
+            func.ST_Y(cast(Place.location, Geometry)).label("lat"),
+        )
+        .join(
+            PlaceContent,
+            and_(
+                PlaceContent.place_id == Place.id,
+                PlaceContent.language == lang,
+                PlaceContent.length == "short",
+            ),
+        )
+        .where(Place.city_id == city.id, Place.is_active.is_(True))
+    )
+    if category is not None:
+        stmt = stmt.where(Place.category == category)
+    if district is not None:
+        stmt = stmt.where(Place.district == district)
+    if q is not None:
+        stmt = stmt.where(PlaceContent.title.ilike(f"%{q}%"))
+
+    rows = db.execute(stmt).all()
+    return [
+        PlaceListItem(id=p.id, slug=p.slug, category=p.category, name=pc.title, location=LatLon(lat=lat, lon=lon))
+        for p, pc, lon, lat in rows
+    ]