Rebuild: coordinator (planner, NNTP pool, spool, prefetcher, leases, rule sets), node API and the edge:node worker

- groups:add / ranges:plan / nodes:create / coordinator:run commands
- the node API: lease, the range's chunks as one framed stream from the
  spool, batches, heartbeat, finish, release (node guard, token per node)
- edge:node: needs COORDINATOR_URL and NODE_TOKEN only (placeholders for
  the rest), posts a batch every 10 chunks, gives its range back on SIGTERM
- releases are gathered per batch: 1.04 chunk rows per release at 10
  chunks per batch (1.35 when built per XOVER chunk)
- partitions are checked per batch instead of remembered

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

config/auth.ts

@@ -20,6 +20,16 @@ const authConfig = defineConfig({
       }),
     }),
 
+    /**
+     * Edge workers (REBUILD.md, part 2): a token per node.
+     */
+    node: tokensGuard({
+      provider: tokensUserProvider({
+        tokens: 'accessTokens',
+        model: () => import('#models/node'),
+      }),
+    }),
+
     /**
      * Session-based guard for browser authentication.
      */