fix: createTile silently drops pinned/savedForLater/reactions + add tile-validation tests

[cobyfrombrooklyn-bot]

Bug Fix

createTile() in db.ts accepted pinned, savedForLater, and reactions in its TypeScript type signature, but the SQL INSERT only wrote id, type, content, source, tags. This meant:

• Creating a tile with pinned: true → tile appears unpinned
• Creating a tile with savedForLater: true → tile appears in main feed
• Creating a tile with reactions → reactions lost

Fix: Added pinned, saved_for_later, and reactions to the INSERT statement.

Tests

Added 25 unit tests for tile-validation.ts covering:

• All tile types (note, song, digest, brief, article, quote, todo)
• Edge cases (null, empty string, invalid year, non-array items, bad audio paths)
• Unknown and flexible types
• Helper functions (getRequiredFields, getAllRequiredFields)
• Immutability of returned config

Also added vitest as a dev dependency and test/test:watch npm scripts.