fix(web): unsaved custom display settings are visible and recoverable

Everything else on the Displays page auto-applies — a preset click, the
game-session choice, the experimental toggles — but the Custom block does
not, and its Save button sat at the bottom of a block taller than most
viewports. People edited, never scrolled far enough to find it, navigated
away, and silently lost the lot.

The draft is now compared against the last-seeded server value, and that
one boolean drives the whole affordance: a badge in the card header
(visible without scrolling), an amber ring plus a title on the block, and
a sticky action bar pinned to the viewport for as long as any part of the
block is on screen. The bar states which of the two states you are in
rather than leaving it implied, Save disables when there is nothing to
save, and Discard changes puts the stored policy back.

Two ways edits could still vanish are closed: a preset click now confirms
before overwriting pending edits, and a reload/close warns. Re-picking
Custom while already on Custom is a no-op instead of re-seeding, which
would otherwise fill in defaults for unset fields and report "unsaved
changes" for a click that changed nothing.

Adds a `warning` badge variant + --warning token for the pending state —
attention, not failure, and distinct from the destructive red.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
(cherry picked from commit c4318609c0da5ae1313081c5e488f685504f70d1)

web/messages/de.json

@@ -136,6 +136,12 @@
   "display_preset_update": "Auf aktuelle Einstellungen aktualisieren",
   "display_preset_delete": "Löschen",
   "display_preset_delete_confirm": "Diese eigene Voreinstellung löschen?",
+  "display_custom_title": "Eigene Einstellungen",
+  "display_unsaved": "Nicht gespeicherte Änderungen",
+  "display_unsaved_hint": "Diese Optionen greifen erst, wenn du speicherst.",
+  "display_all_saved": "Alle Änderungen gespeichert",
+  "display_revert": "Änderungen verwerfen",
+  "display_discard_confirm": "Du hast nicht gespeicherte eigene Einstellungen. Verwerfen?",
   "clients_title": "Gekoppelte Geräte",
   "clients_empty": "Noch keine gekoppelten Geräte.",
   "clients_name": "Name",