fix(modal): pin Related to rail bottom, floppy-disk download, drop suggestions cap

Right-rail layout fixes (operator-flagged 2026-06-26 — the prior change wasn't
the intended improvement):

- Pin the Related strip to the BOTTOM of the rail: the side becomes a flex
  column with a scrolling main area (meta + provenance + tags + suggestions)
  and a pinned Related footer (capped at 45% of the rail, scrolls past that).
  Related now stays reachable no matter how long Tags/Suggestions run, and
  self-collapses (no footer space) when there's nothing to show.
- Remove the 320px suggestions scroll cap (3fcc4ae) — it was a workaround "so
  Related stays reachable"; pinning Related is the proper fix, so suggestions
  flow in the single main scroll instead of a nested scrollbar.
- Shrink the Download button to a floppy-disk save icon (mdi-content-save); the
  meta (dimensions/size/type) + save action now sit as a compact top block
  (meta left, icon right). Copy link moves into the adjacent kebab menu.

ImageMetaBar is shared with the Explore center pane, so the compact save
control applies there too (parity). Mobile (<=900px) keeps the single body
scroll — no nested scroll, Related flows at the end.

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

frontend/src/components/modal/SuggestionsPanel.vue

@@ -12,10 +12,9 @@
       No suggestions above threshold.
     </div>
 
-    <!-- Scroll-capped so a long suggestion set (the General bucket can run to
-         dozens) scrolls WITHIN this box instead of stretching the right rail
-         and shoving the Related strip below the fold. Mirrors the
-         ProvenancePanel cards/attachments treatment. -->
+    <!-- Flows in the rail's main scroll area; Related is pinned to the bottom
+         of the rail (ImageViewer side layout), so a long suggestion set no
+         longer needs an internal scroll cap to keep Related reachable. -->
     <div v-else class="fc-suggestions__list">
       <SuggestionsCategoryGroup
         v-for="cat in peopleCats" :key="cat"
@@ -137,13 +136,9 @@ async function onRemoveAlias(s) {
   margin-bottom: 8px;
 }
 .fc-suggestions__list {
-  /* Cap the suggestion run so it scrolls internally rather than pushing the
-     Related strip off the bottom of the rail. Hairline scrollbar matching
-     ProvenancePanel's capped regions. */
-  max-height: 320px;
-  overflow-y: auto;
-  scrollbar-width: thin;
-  scrollbar-color: rgb(var(--v-theme-surface-light)) transparent;
+  /* No internal scroll cap: the rail now scrolls suggestions in its single
+     main scroll area while Related is pinned to the bottom (ImageViewer side
+     layout), so suggestions flow naturally without a nested scrollbar. */
   padding-right: 4px;
 }
 .fc-suggestions__skeleton { display: flex; flex-direction: column; gap: 8px; }