fix(a11y): resolve serious accessibility issues on search page (GOO-110)

- Add aria-hidden="true" to all decorative inline SVGs (bookmark, view-mode, funnel, checkmark)
- Convert save-search popover to proper dialog: role="dialog", aria-modal, focus trap, Escape key, focus return to trigger
- Add aria-pressed on list/map/split view-mode toggle buttons
- Add aria-expanded + aria-controls on mobile filter toggle button
- Add role="status" + aria-label="Đang tải..." on Suspense fallback

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/modules/read-models/domain/read-model-kill-switch.ts

@@ -0,0 +1,24 @@
+/**
+ * Per-read-model kill switch — RFC-003 §0.
+ *
+ * Contract:
+ *   - `isEnabled(name)` returns whether the named read model should
+ *     serve queries. When `false`, callers MUST fail open to the
+ *     write-model path.
+ *   - Implementations MUST be hot-readable (no restart required).
+ *   - The check is evaluated per-call so that a flag toggled mid-request
+ *     is honoured on the NEXT repository call within the same request.
+ *     In-flight calls complete against whichever source they already
+ *     started on.
+ */
+
+export const READ_MODEL_KILL_SWITCH = Symbol('READ_MODEL_KILL_SWITCH');
+
+export interface IReadModelKillSwitch {
+  /**
+   * Returns `true` when the named read model is active and safe to query.
+   * Returns `true` (fail-open) for unknown / un-configured names so that
+   * an absent config key never blocks the write-model fallback path.
+   */
+  isEnabled(readModelName: string): boolean;
+}