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/components/cases/drafts-panel.tsx

@@ -38,6 +38,7 @@ import {
 import { useCaseCitations } from "@/lib/api/citations";
 import { learningKeys } from "@/lib/api/learning";
 import { LearningStatusBadges } from "@/components/cases/learning-status-badges";
+import { formatDateTime, formatDateShort } from "@/lib/format-date";
 import type { CaseStatus } from "@/lib/api/cases";
 import { toast } from "sonner";
 import {
@@ -72,13 +73,7 @@ function formatSize(bytes: number): string {
 }
 
 function formatDate(epoch: number): string {
-  return new Date(epoch * 1000).toLocaleDateString("he-IL", {
-    day: "numeric",
-    month: "short",
-    year: "numeric",
-    hour: "2-digit",
-    minute: "2-digit",
-  });
+  return formatDateTime(epoch * 1000);
 }
 
 /* ── Main component ─────────────────────────────────── */
@@ -568,9 +563,7 @@ export function DraftsPanel({
                     </Badge>
                   )}
                   <span className="text-[0.65rem] text-ink-muted me-auto">
-                    {fb.created_at
-                      ? new Date(fb.created_at).toLocaleDateString("he-IL")
-                      : ""}
+                    {fb.created_at ? formatDateShort(fb.created_at) : ""}
                   </span>
                 </div>
                 <p className="text-sm leading-relaxed">{fb.feedback_text}</p>