feat(ops): self-heal disk pressure instead of only alerting

The 5-minute disk probe now reclaims storage automatically: from 85% it runs the gentle age-windowed Docker prune, from 90% it drops the age windows (docker-prune.sh --force: all unused build cache and unreferenced images, all stopped containers) so a mount can never silently max out. Alerts still fire at 85/90/95% and their hint now points at non-Docker growth when reclaiming is not enough. Force mode is reserved for the worker; deploys keep the gentle mode. Volumes are off-limits in every path.

src/lib/services/alert.ts

@@ -306,7 +306,7 @@ export function diskPressure(usage: {
 			used: formatBytes(usage.usedBytes),
 			total: formatBytes(usage.totalBytes),
 			available: formatBytes(usage.availableBytes),
-			hint: "Docker prune runs nightly; run scripts/docker-prune.sh to reclaim cache sooner.",
+			hint: "Docker cache reclaim auto-fired with this alert; if the disk is still filling, the growth is outside Docker (check Gamedata/uploads/storage).",
 		},
 	});
 }