Initial boilerplate scaffold for continuum-backend

Bun + ElysiaJS control plane: Drizzle/Postgres schema (printers, farms,
print_jobs, pgvector frame_embeddings), R2 presigned URLs, Redis Streams
frame ingestion queue, REST routes, and the /ws/edge/v1 edge-gateway
WebSocket uplink.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,7 @@
+node_modules/
+dist/
+.env
+.env.local
+drizzle/
+*.log
+.DS_Store