fix(bluesky): correct ATProto location schema for event creation

[tompscanlan]

Summary

• Fix Bluesky event creation failing with "Bad record" errors for events with physical locations
• ATProto lexicon schema mismatch was causing PDS validation failures

Changes

• Use $type discriminator instead of type for union types
• Use latitude/longitude (strings) instead of lat/lon (numbers)
• Use name field instead of description for geo locations
• Update BlueskyTypes.ts with properly typed interfaces

Root Cause

The code was sending:

{ type: 'community.lexicon.location.geo', lat: 38.27, lon: -85.64, description: '...' }

But the lexicon requires:

{ $type: 'community.lexicon.location.geo', latitude: '38.27', longitude: '-85.64', name: '...' }

Test plan

• Added unit tests for geo location schema
• Added unit tests for URI location schema
• Added unit tests for hybrid events with both location types
• Manual test: Create event with physical location and publish to Bluesky
• Manual test: Verify event appears correctly on Bluesky

Reported by: seth.computer on Bluesky