fix(web-ui): display all human-facing timestamps in Asia/Jerusalem (deterministic)

Storage stays UTC (DB TIMESTAMPTZ, API ISO-UTC) — only the display layer is
localized, and now deterministically: every timestamp renders pinned to
Asia/Jerusalem via a single Intl-based formatter, so SSR (UTC container) and
the browser agree on any runtime. No layout/visible-format change — only the tz.

- New single date formatter web-ui/src/lib/format-date.ts (G2): formatDate /
  formatDateShort / formatDateLong / formatDateTime / formatDateTimeFull /
  formatTime / formatIsoDate + Israel helpers getIsraelYear / israelDayKey /
  israelMidnightMs / israelParts + formatRelative (long/short/tight wording).
- Routed all ad-hoc toLocaleDateString/toLocaleTimeString/toLocaleString +
  hand-rolled new Date(...).get*() / toISOString().slice(0,10) timestamp call
  sites (30 files) through it. Number toLocaleString left untouched.
- Spec: added INV-UI9 to docs/spec/X6 (UTC storage, Asia/Jerusalem display).

Display-only; no layout/design/IA change → Claude Design gate N/A.
Invariants: G2 (single date formatter, no parallel ad-hoc formatting), INV-UI9.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web-ui/src/app/feedback/page.tsx

@@ -16,6 +16,7 @@ import {
   type ChairFeedback,
   type FeedbackCategory,
 } from "@/lib/api/feedback";
+import { formatDateLong } from "@/lib/format-date";
 
 /**
  * מרכז הערות יו"ר — הדף המרכזי לטיפול בכל הערות דפנה שנרשמו על טיוטות
@@ -33,18 +34,7 @@ const CAT_CHIP: Record<FeedbackCategory, string> = {
   other: "bg-rule-soft text-ink-soft",
 };
 
-function formatDate(iso?: string | null): string {
-  if (!iso) return "";
-  try {
-    return new Date(iso).toLocaleDateString("he-IL", {
-      day: "numeric",
-      month: "long",
-      year: "numeric",
-    });
-  } catch {
-    return "";
-  }
-}
+const formatDate = (iso?: string | null) => formatDateLong(iso);
 
 function FeedbackCard({ fb }: { fb: ChairFeedback }) {
   const resolve = useResolveFeedback();