chore: purge retired git.tx1138.com registry host from the codebase

The tx1138 Gitea was retired as a release server 2026-06-13 and its registry
frontend is fully dead (500 on every /v2 manifest read, observed 2026-07-10).
Nothing may reference it anymore:

- registry.rs: no longer a default registry, no longer force-enabled on
  load; saved configs are stripped of it on load (same one-time migration
  treatment as the decommissioned Hetzner mirror), with a regression test.
- image_policy.rs: removed from TRUSTED_REGISTRIES — refs through the dead
  host are now refused at the pull site (rejection test added).
- api/handler: dropped the legacy catalog-proxy fallback URL.
- .gitmodules: indeedhub submodule repointed to the OVH Gitea.
- scripts, image-recipe, app-catalog data, neode-ui strings, docs, and all
  test fixtures repointed to 146.59.87.168:3000 (or neutral example hosts).
- image-versions.sh: ARCHY_REGISTRY_FALLBACK emptied (guarded consumers
  skip it); reconcile-containers.sh candidate guard hardened.

The only remaining occurrences of the host string are the strip/reject
enforcement paths and their regression tests — the code that guarantees it
is never used again.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

scripts/bootstrap-switchover.sh

@@ -78,7 +78,7 @@ if $DOCKER ps -a --format '{{.Names}}' 2>/dev/null | grep -q '^electrumx$'; then
         -e "DAEMON_URL=http://${RPC_USER}:${RPC_PASS}@bitcoin-knots:8332/" \
         -e COIN=Bitcoin -e DB_DIRECTORY=/data \
         -e "SERVICES=tcp://:50001,rpc://0.0.0.0:8000" \
-        "${ELECTRUMX_IMAGE:-git.tx1138.com/lfg2025/electrumx:v1.18.0}"
+        "${ELECTRUMX_IMAGE:-146.59.87.168:3000/lfg2025/electrumx:v1.18.0}"
 fi
 
 # Mempool API
@@ -98,7 +98,7 @@ if $DOCKER ps -a --format '{{.Names}}' 2>/dev/null | grep -q '^mempool-api$'; th
         -e "DATABASE_ENABLED=true" -e "DATABASE_HOST=archy-mempool-db" \
         -e "DATABASE_DATABASE=mempool" -e "DATABASE_USERNAME=mempool" \
         -e "DATABASE_PASSWORD=$(cat "$SECRETS_DIR/mempool-db-password" 2>/dev/null || echo mempoolpass)" \
-        "${MEMPOOL_API_IMAGE:-git.tx1138.com/lfg2025/mempool-api:v3.2.0}"
+        "${MEMPOOL_API_IMAGE:-146.59.87.168:3000/lfg2025/mempool-api:v3.2.0}"
 fi
 
 # Stop Tor tunnel if it was active