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>

drizzle.config.ts

@@ -0,0 +1,12 @@
+import { defineConfig } from "drizzle-kit";
+
+export default defineConfig({
+  schema: "./src/db/schema/index.ts",
+  out: "./drizzle",
+  dialect: "postgresql",
+  dbCredentials: {
+    url: process.env.DATABASE_URL ?? "postgres://continuum:continuum@localhost:6432/continuum",
+  },
+  verbose: true,
+  strict: true,
+});