Add hierarchical route grouping for multi-area locations

Locations like Mt. Moon (with 1F, B1F, B2F floors) are now grouped so
only one encounter can be logged per location group, enforcing Nuzlocke
first-encounter rules correctly.

- Add parent_route_id column with self-referential FK to routes table
- Add parent/children relationships on Route model
- Update games API to return hierarchical route structure
- Add validation in encounters API to prevent parent route encounters
  and duplicate encounters within sibling routes (409 conflict)
- Update frontend with collapsible RouteGroup component
- Auto-derive route groups from PokeAPI location/location-area structure
- Regenerate seed data with 70 parent routes and 315 child routes

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/src/app/seeds/fetch_pokeapi.py

@@ -187,7 +187,11 @@ def aggregate_encounters(raw_encounters: list[dict]) -> list[dict]:
 
 
 def process_version(version_name: str, vg_info: dict) -> list[dict]:
-    """Process all locations for a specific game version."""
+    """Process all locations for a specific game version.
+
+    Creates hierarchical route structure where locations with multiple areas
+    become parent routes with child routes for each area.
+    """
     print(f"\n--- Processing {version_name} ---")
 
     region = load_resource("region", vg_info["region_id"])
@@ -230,8 +234,38 @@ def process_version(version_name: str, vg_info: dict) -> list[dict]:
             else:
                 all_encounters.extend(encounters)
 
-        # Area-specific encounters become separate routes
-        if area_specific:
+        # If we have multiple area-specific encounters, create a parent route
+        # with child routes for each area (hierarchical grouping)
+        if area_specific and len(area_specific) > 1:
+            # Create parent route (no encounters - just a logical grouping)
+            parent_order = order
+            order += 1
+
+            child_routes = []
+            for area_suffix, area_encs in area_specific.items():
+                aggregated = aggregate_encounters(area_encs)
+                if aggregated:
+                    route_name = f"{display_name} ({area_suffix})"
+                    for enc in aggregated:
+                        all_pokemon_dex.add(enc["national_dex"])
+                    child_routes.append({
+                        "name": route_name,
+                        "order": order,
+                        "encounters": aggregated,
+                    })
+                    order += 1
+
+            # Only add parent if we have child routes
+            if child_routes:
+                routes.append({
+                    "name": display_name,
+                    "order": parent_order,
+                    "encounters": [],  # Parent routes have no encounters
+                    "children": child_routes,
+                })
+
+        elif area_specific:
+            # Only one area-specific route - don't create parent/child, just use suffix
             for area_suffix, area_encs in area_specific.items():
                 aggregated = aggregate_encounters(area_encs)
                 if aggregated:
@@ -245,6 +279,7 @@ def process_version(version_name: str, vg_info: dict) -> list[dict]:
                     })
                     order += 1
 
+        # Non-area-specific encounters (or single area without suffix)
         if all_encounters:
             aggregated = aggregate_encounters(all_encounters)
             if aggregated:
@@ -257,8 +292,13 @@ def process_version(version_name: str, vg_info: dict) -> list[dict]:
                 })
                 order += 1
 
-    print(f"  Routes with encounters: {len(routes)}")
-    total_enc = sum(len(r["encounters"]) for r in routes)
+    # Count routes including children
+    total_routes = sum(1 + len(r.get("children", [])) for r in routes)
+    print(f"  Routes with encounters: {total_routes}")
+    total_enc = sum(
+        len(r["encounters"]) + sum(len(c["encounters"]) for c in r.get("children", []))
+        for r in routes
+    )
     print(f"  Total encounter entries: {total_enc}")
 
     return routes