feat: add getRepo endpoint returning CAR file

Converts ArrayBuffer from SQLite BLOB to Uint8Array before building CAR.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[e-mail]>

src/pds.js

···
 
       return Response.json({ uri, cid: row.cid, value })
     }
+    if (url.pathname === '/xrpc/com.atproto.sync.getRepo') {
+      const commits = this.sql.exec(
+        `SELECT cid FROM commits ORDER BY seq DESC LIMIT 1`
+      ).toArray()
+
+      if (commits.length === 0) {
+        return Response.json({ error: 'repo not found' }, { status: 404 })
+      }
+
+      const blocks = this.sql.exec(`SELECT cid, data FROM blocks`).toArray()
+      // Convert ArrayBuffer data to Uint8Array
+      const blocksForCar = blocks.map(b => ({
+        cid: b.cid,
+        data: new Uint8Array(b.data)
+      }))
+      const car = buildCarFile(commits[0].cid, blocksForCar)
+
+      return new Response(car, {
+        headers: { 'content-type': 'application/vnd.ipld.car' }
+      })
+    }
     return new Response('pds running', { status: 200 })
   }
 }