catalog: re-pin wanderer to the current upstream shape, retire plant-it, add the resolvability gate

wanderer: ghcr.io/flomp/wanderer:0.16.0 is a ghost - upstream split the app
into web+db images, moved registry and renamed the org. Restructured to
upstream's own v0.20.0 compose (3 services, new /data/plugins volume, second
public hostname for PocketBase, meilisearch pinned DOWN to upstream's v1.36.0
per the R-42 ruling).

plant-it: retired. The repo name was wrong (plant-it-server) but upstream has
DELETED self-hosting; last server image is 2024-12-10 and it needs MySQL+Redis
the template never had. Moved to retired/ rather than deleted - reversible.

R-41 slice 1: check-image-resolvable.py. Encodes two traps - manifest inspect
exits 0 while printing toomanyrequests, and the inverse, where the first sweep
called 24 of 65 pins dead because Hub throttled it. Ambiguity is INCONCLUSIVE,
never an accusation.

CLAUDE.md

@@ -31,3 +31,11 @@ deployed `app.yaml` (customer secrets) is never overwritten. Full deploy details
   anywhere in the fleet is pinned to the digest it is currently running (a pin must never cause a
   version jump). Digest pins (`@sha256:`) also count. Gate: `python scripts/check-image-pins.py`
   (run after any compose change; exit 1 on any floating/missing tag).
+- **A pinned tag can still rot away upstream** — the pin gate is syntactic and cannot see that.
+  Second gate: `python3 scripts/check-image-resolvable.py` (exit 0 resolve / 1 GONE / 2 inconclusive),
+  run at the start of every catalog campaign and before any publish train that vouches the catalog.
+  Needs network + `docker`; unauthenticated Docker Hub throttles a full sweep, so `docker login`
+  first or expect exit 2. It reports a throttle as INCONCLUSIVE, never as a dead image.
+- **Retiring an app**: `git mv templates/<app> retired/<app>` (see `retired/README.md`) — the sync
+  discovers apps by directory, so this un-offers it while keeping it revivable. Sync never removes a
+  stack dir it already copied, so retirement freezes the app on existing boxes rather than deleting it.