tsc only emits .ts -> .js; non-TypeScript assets like SQL migration
files don't make it into dist/ by default. The migration runner reads
*.sql from dist/db/migrations/ at runtime in production (relative to
the compiled migrate.js), so the missing files surface as a fatal
ENOENT on container startup.
Fix: small node script (scripts/copy-assets.mjs) using fs.cpSync,
invoked after tsc in the build script. Cross-platform, no new
dependencies. The script is in the Docker build context but not
copied into the runtime stage, so it doesn't bloat the final image.
Verified: pnpm build now produces dist/db/migrations/0001_positions.sql.
