feat: Add city filtering to bicycle-racks API

[dvalenca]

🚀 Overview
Enhanced the bicycle-racks API with optional city filtering capability, allowing users to query data for specific cities or retrieve all data from Brazil.

🔧 Changes Made
Database Schema
Added bicycle_rack_cities table to map OSM IDs to cities for efficient filtering

Updated seed process to populate city mappings from Recife-specific GeoJSON data

Added conflict handling with onConflictDoNothing() for duplicate OSM IDs

API Enhancements
Added optional city parameter to all bicycle-racks endpoints:

GET /v1/bicycle-racks?city=Recife

GET /v1/bicycle-racks/geojson?city=Recife

GET /v1/bicycle-racks/stats?city=Recife

GET /v1/bicycle-racks/nearby?city=Recife&lat=-8.0631&lng=-34.8713&radius=1000

Performance Optimization
JOIN-based filtering instead of PostGIS radius queries for better performance

Efficient hash join strategy executing in ~1.7ms for city-specific queries

📊 Data Results
Total Brazil: 5,598 bicycle racks

Recife only: 578 bicycle racks (when city=Recife)

Performance: Fast queries using indexed JOIN operations

🧪 Testing
Added comprehensive SQL test queries (41 total) to validate:

City filtering functionality

Data quality analysis

Performance benchmarking

Capacity anomaly investigation

🔄 API Flexibility
Without city parameter: Returns all Brazil data

With city=Recife: Returns only Recife data

Extensible: Ready for additional cities as data becomes available

✅ Validation
All endpoints tested with curl and confirmed working:

Stats: 5,598 total → 578 for Recife

GeoJSON: 5,598 features → 578 for Recife

Nearby: Location-based filtering within city boundaries