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>

app/models/node.ts

@@ -0,0 +1,8 @@
+import { NodeSchema } from '#database/schema'
+import { type AccessToken, DbAccessTokensProvider } from '@adonisjs/auth/access_tokens'
+
+/** An edge worker (REBUILD.md, part 2); it authenticates with an access token (the `node` guard). */
+export default class Node extends NodeSchema {
+  static accessTokens = DbAccessTokensProvider.forModel(Node, { table: 'node_access_tokens' })
+  declare currentAccessToken?: AccessToken
+}