Prober: no claims under PROBE_MIN_FREE_GB free on the NVMe

At ~200 articles/s what the prober stores (inspections, par2 file lists,
the WAL) took ~0.8-1.1 GB an hour of homelab's root, and nothing stopped it
at the 10 GB floor. Below 12 GB free it claims nothing (resumed 1 GB above):
the lanes go dry and its share shrinks to its minimum.

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

app/services/prober.ts

@@ -7,6 +7,7 @@ import { XoverClient } from '#lib/nntp/index'
 import { YencError } from '#lib/yenc/index'
 import { inspect, innerName, PROBE_VERSION, type Inspection } from '#lib/probe/index'
 import { NntpShare } from '#services/nntp_shares'
+import { DiskSpace } from '#services/disk_space'
 
 interface Candidate {
   id: number
@@ -52,6 +53,8 @@ export class Prober {
   private running = 0
   /** The last lane to look found nothing to claim: the prober wants its minimum only. */
   private dry = false
+  /** What it stores (inspections, par2 file lists, the WAL) fills the NVMe: no claims below PROBE_MIN_FREE_GB. */
+  private space = new DiskSpace('probing', '/', coordinatorConfig.probe.minFreeGb)
   private share = new NntpShare('prober', coordinatorConfig.nntpShares.proberPriority, coordinatorConfig.probe.minConnections, coordinatorConfig.probe.connections)
 
   /** Per minute: what was read, and where the lanes' time went (ms summed over lanes; flushes ms on their own). */
@@ -201,6 +204,8 @@ export class Prober {
   }
 
   private async claimTiers() {
+    // The queue empties, the lanes go dry and the share shrinks to its minimum until there's room again.
+    if (await this.space.short()) return
     for (const { kind, unreadable } of TIERS) {
       const want = this.batch - this.queue.length
       if (want <= 0) return