Refactor to Drizzle ORM and add baseline schema migration

[KyleTryon]

This pull request migrates the server database layer from a custom, homegrown migration system to Drizzle ORM's built-in migration system. It removes legacy migration code, adds Drizzle migrations and related scripts, and introduces a safety check to prevent using old databases without proper migration state. The Docker build and runtime are updated to include Drizzle migration files.

Database migration system migration:

• Removed the legacy migration system by deleting runMigrations and all custom migration logic from apps/server/src/db/migrations.ts, and removed the schema_migrations table from apps/server/src/db/schema.ts. [1] [2]
• Switched to Drizzle ORM migrations in apps/server/src/db/database.ts, using Drizzle's migrate function and referencing the Drizzle migrations folder. [1] [2]

Drizzle migration setup:

• Added initial Drizzle migration SQL in apps/server/drizzle/20260418064431_baseline/migration.sql, recreating the schema and indexes for provider_accounts, media_sources, and provider_sessions.
• Added a new script db:export to apps/server/package.json for exporting Drizzle migrations as SQL.

Safety and compatibility checks:

• Added prepareDatabaseForMigrations in apps/server/src/db/migrationState.ts to detect and prevent use of pre-release databases without Drizzle migration state, requiring users to delete old data directories if detected.

Dockerfile updates:

• Updated the Docker build and runtime to copy the Drizzle migrations folder, ensuring migrations are available in production containers. [1] [2]