ui(thumbs): remove the "date may be wrong" badge

The amber AlertTriangle in the bottom-right of every photo with
has_date_warning set was more visual noise than help — the filter pill's
"Date issues" option still surfaces the same photos when the user
actually wants to triage them. Keeps the BR corner uncluttered.

Backend field + filter pill option unchanged.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/components/timeline/PhotoThumbnail.tsx

@@ -4,7 +4,6 @@ import {
   Trash2,
   RefreshCw,
   Copy,
-  AlertTriangle,
   Users,
   ShoppingBasket,
 } from 'lucide-react'
@@ -114,13 +113,6 @@ function PhotoThumbnailImpl({
   const sep = baseUrl.includes('?') ? '&' : '?'
   const thumbnailUrl = retryCount > 0 ? `${baseUrl}${sep}retry=${retryCount}` : baseUrl
 
-  // "Capture date probably wrong" — read straight from the stored
-  // `has_date_warning` flag rather than recomputing the heuristic
-  // client-side. The backend sets this column at scan time and
-  // refreshes it on any taken_at edit, so the UI, the filter, and the
-  // thumbnail badge all read from one source of truth.
-  const dateWarning = photo.has_date_warning === true
-
   // Square cells (Lightroom-style grid). Variable-aspect cells previously
   // overflowed their row because TanStack Virtual estimates row height as a
   // single fixed value — portraits in a landscape row would overlap the row
@@ -375,10 +367,9 @@ function PhotoThumbnailImpl({
         </div>
       )}
 
-      {/* BR — duplicate / discard / date-warning (neutral info) plus a
+      {/* BR — duplicate / discard (neutral info) plus a heap-membership
-       *  heap-membership chip. The green tint overlay above is the
+       *  chip. The green tint overlay above is the primary signal, but
-       *  primary signal, but the icon makes membership readable in
+       *  the icon makes membership readable in colorblind-safe terms too. */}
-       *  colorblind-safe terms too. */}
       <div className="absolute bottom-1 right-1 flex items-center gap-1">
         {isInActiveHeap && (
           <div
@@ -408,21 +399,6 @@ function PhotoThumbnailImpl({
             <Trash2 className={THUMB_BADGE_ICON} strokeWidth={2.5} />
           </div>
         )}
-        {dateWarning && (
-          <div
-            className={cn(
-              THUMB_BADGE_BASE,
-              THUMB_BADGE_SQUARE,
-              // Amber fill with the same chiseled frame as other affirmative
-              // badges so it reads as a first-class warning rather than a
-              // neutral info chip.
-              'bg-amber-500 shadow-[0_0_0_1px_rgba(0,0,0,0.55),inset_0_1px_0_rgba(255,255,255,0.28),0_1px_2px_rgba(0,0,0,0.5)]'
-            )}
-            title="Capture date may be wrong — folder/filename suggests a different date"
-          >
-            <AlertTriangle className={THUMB_BADGE_ICON} strokeWidth={2.5} />
-          </div>
-        )}
       </div>
 
       {/* TR — file-type metadata (RAW / VIDEO) */}