refactor: replace custom migrate.ts with standard Drizzle migrator

The baseline/bogus-entry logic was a one-time workaround for a db:push
→ migration transition that is long past. It required a per-migration
isMigrationApplied case — missing cases caused today's invoiceId bug.
Now both db:migrate (dev) and Docker startup use the same standard
migrate() call. Drizzle's own tracking table handles idempotency.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

package.json

@@ -7,7 +7,7 @@
     "build": "next build",
     "check": "eslint . && tsc --noEmit",
     "db:generate": "drizzle-kit generate",
-    "db:migrate": "bun drizzle-kit migrate",
+    "db:migrate": "bun src/server/db/migrate.ts",
     "db:push": "drizzle-kit push",
     "db:studio": "drizzle-kit studio",
     "db:clone": "./scripts/clone-local.sh",