Create or update Convex schema with proper indexes and validators
# Create/Update Convex Schema
Update the Convex schema in `convex/schema.ts` following best practices:
1. Use `defineSchema` and `defineTable` from "convex/server"
2. Use proper validators from `v` in "convex/values"
3. Define indexes for all query patterns
4. Include `authTables` if using Convex Auth
Schema changes for: $ARGUMENTS
Follow these rules:
- System fields `_id` and `_creationTime` are automatic - don't define them
- NEVER create `.index("by_creation_time", ["_creationTime"])` - it's built-in
- NEVER include `_creationTime` as the last field in an index - it's automatic
- Ind...