Migrate hardcoded place data from LondonSeedData.java to JSON file loaded via PlaceDataService

[HHassancoding]

Tasks

• Migrate place data out of LondonSeedData.java into src/main/resources/data/london-places.json.

• Create PlaceDataService to load the JSON once at startup using @PostConstruct and ObjectMapper.

• Refactor RecommendationService to use PlaceDataService instead of LondonSeedData.

• Delete LondonSeedData.java once the app is confirmed working.