feat(mcpedia): Phase 3 — async indexing (BullMQ), git-sync webhook, revisions, MCP Resources

- packages/queue: ioredis singleton + BullMQ Queue/Worker (prefix mcpedia:
  on shared imrnes Redis :6379); apps/worker runs startWorker()
- @mcpedia/core: indexContentFile/runFullIndex (single indexing entry point
  shared by script/worker/hook) + revision.service (list/get/restore)
- document_revisions table (migration 0002) — snapshots only on body change
- apps/api: POST /hooks/reindex + /hooks/index webhooks; tRPC revisions,
  getRevision, restoreRevision, jobStatus, queueStatus
- apps/mcp: register MCP Resources mcpedia://docs{/,+slug/chunks/revisions}
  ({+slug} RFC6570 reserved expansion for slugs containing /)
- apps/mcp zod pinned to ^4 to match MCP SDK 1.30 compiled types
  (resolves registerTool TS2589/ShapeOutput skew)
- scripts/enqueue.ts one-shot job enqueue helper; indexer refactored to runFullIndex
- PHASES.md/README/.env.example/docs updated

packages/queue/src/worker.ts

@@ -0,0 +1,63 @@
+import { Worker, type Job } from "bullmq";
+import { getConnection, BULLMQ_PREFIX } from "./client";
+import { INDEX_QUEUE } from "./queue";
+import { indexContentFile, runFullIndex } from "@mcpedia/core";
+
+export function createWorker(): Worker {
+  const worker = new Worker(
+    INDEX_QUEUE,
+    async (job: Job) => {
+      switch (job.name) {
+        case "index-doc": {
+          const { relPath, reason } = job.data as {
+            relPath: string;
+            reason: string;
+          };
+          await job.log(`indexing ${relPath}`);
+          const r = await indexContentFile(relPath, reason);
+          return r;
+        }
+        case "index-all": {
+          const { reason } = job.data as { reason: string };
+          await job.log(`full index (${reason})`);
+          return await runFullIndex(reason);
+        }
+        default:
+          throw new Error(`unknown job type: ${job.name}`);
+      }
+    },
+    {
+      connection: getConnection(),
+      prefix: BULLMQ_PREFIX,
+      concurrency: 4,
+    },
+  );
+
+  worker.on("completed", (job) => {
+    console.log(`[worker] completed ${job.name} (${job.id})`);
+  });
+  worker.on("failed", (job, err) => {
+    console.error(`[worker] failed ${job?.name} (${job?.id}): ${err.message}`);
+  });
+  worker.on("error", (err) => {
+    console.error(`[worker] error:`, err.message);
+  });
+
+  return worker;
+}
+
+/** Start the worker and wire graceful shutdown. */
+export async function startWorker(): Promise<Worker> {
+  const worker = createWorker();
+  console.log("[worker] indexing worker started");
+
+  const shutdown = async (sig: string) => {
+    console.log(`[worker] ${sig} received, closing...`);
+    await worker.close();
+    process.exit(0);
+  };
+  process.on("SIGINT", () => void shutdown("SIGINT"));
+  process.on("SIGTERM", () => void shutdown("SIGTERM"));
+
+  return worker;
+}