controller v0.265.0: R-634 cause fixed, held apps say so, OOM storm alarm, R-647 leftovers

R-634: a whole-box backup no longer stops/restarts a DEPLOYING app (the
measured cause of containers running under 'not deployed'); StopStack
and StartStack refuse a deploying stack for every caller.
R-625: held badge 'Stopped - restore needed', no Update button.
R-636: kernel oom_kill counter; 20+ in 30 min -> one app_oom_storm.
R-647: held error per reader, copy_holds key, two log wordings.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

controller/internal/web/testdata/i18n_parity/stacks_full.html

@@ -252,7 +252,7 @@
             <span class="tag tag-neutral"><span class="dot"></span>Leállítva</span>
             
             
-            
+            <span class="tag tag-error" title="A frissítés megállt, a mentés hiányzik.">Megállítva — visszaállítás szükséges</span>