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/coordinator.ts

@@ -0,0 +1,24 @@
+import env from '#start/env'
+import app from '@adonisjs/core/services/app'
+
+/** The coordinator (REBUILD.md, part 1). */
+export default {
+  /** Articles per range. */
+  rangeArticles: env.get('RANGE_ARTICLES', 2_000_000),
+  /** Articles per XOVER chunk (spool files, stream frames). */
+  chunkArticles: env.get('CHUNK_ARTICLES', 50_000),
+  /** A leased range without a heartbeat for this long goes back to the queue. */
+  leaseTtlSeconds: env.get('LEASE_TTL_SECONDS', 15 * 60),
+  /** NNTP connections the coordinator fetches headers with. */
+  nntpConnections: env.get('NNTP_CONNECTIONS', 4),
+  /** A reply with no data for this long fails (old ranges answer slowly). */
+  nntpTimeoutMs: env.get('NNTP_TIMEOUT_MS', 10 * 60 * 1000),
+  spool: {
+    dir: env.get('SPOOL_DIR', app.tmpPath('spool')),
+    /** Ranges kept fetched ahead, per active lease. */
+    aheadPerLease: env.get('SPOOL_AHEAD_PER_LEASE', 2),
+    /** At least this many ranges ahead, so the first leases start at once. */
+    minAhead: env.get('SPOOL_MIN_AHEAD', 2),
+    maxBytes: env.get('SPOOL_MAX_GB', 10) * 1e9,
+  },
+}