feat(suggestions): user-managed blocklist for noisy auto-tags

Adds a tag_suggestion_blocklist table + service-layer filter so the
user can permanently suppress specific canonical tag names from the
suggestion stream (WD14 anatomy/composition tags like '1girl',
'breasts', 'nipples' that aren't useful for the discoverability use
case this app targets).

Data model
  - migration k26042201: tag_suggestion_blocklist(name TEXT PK, created_at)
  - model TagSuggestionBlocklistEntry

Service
  - tag_suggestions._blocklisted_names() snapshots the current set
  - get_suggestions filters merged results before grouping, so both
    WD14- and embedding-sourced suggestions respect the blocklist
  - get_bulk_suggestions inherits the filter via its per-image call
    to get_suggestions

API
  - GET  /api/suggestions/blocklist           -> {ok, names}
  - POST /api/suggestions/blocklist           -> add one
  - POST /api/suggestions/blocklist/delete    -> remove one
  - POST /api/suggestions/blocklist/bulk      -> replace the whole list
    (backs the settings textarea save button)

UI
  - modal suggestion chip gets a third action button (⊘) alongside
    accept (✓) / reject (✕). Clicking it adds the name to the
    blocklist, logs a rejection for ML feedback on this image, and
    sweeps every chip on the page carrying that same name.
  - Settings -> Maintenance -> Suggestion blocklist section with a
    monospaced textarea (one name per line) + Save. Loads current
    entries on mount.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/static/js/view-modal.js

@@ -144,19 +144,70 @@ document.addEventListener('DOMContentLoaded', () => {
         <span class="sugg-confidence">${pct}%</span>
       </span>
       <button type="button" class="sugg-btn sugg-reject" aria-label="Reject">✕</button>
+      <button type="button" class="sugg-btn sugg-block" aria-label="Never suggest this tag" title="Never suggest '${escapeHtml(suggestion.name)}' again">⊘</button>
     `;
 
     const acceptBtn = chip.querySelector('.sugg-accept');
     const rejectBtn = chip.querySelector('.sugg-reject');
+    const blockBtn  = chip.querySelector('.sugg-block');
     if (acceptBtn) {
       acceptBtn.addEventListener('click', () => acceptSuggestion(chip, imageId));
     }
     if (rejectBtn) {
       rejectBtn.addEventListener('click', () => rejectSuggestion(chip, imageId));
     }
+    if (blockBtn) {
+      blockBtn.addEventListener('click', () => blocklistSuggestion(chip, imageId));
+    }
     return chip;
   }
 
+  async function blocklistSuggestion(chip, imageId) {
+    if (chip.dataset.disabled === 'true') return;
+    chip.dataset.disabled = 'true';
+    chip.style.pointerEvents = 'none';
+    const name = chip.dataset.tagName;
+    try {
+      // Add to the user's blocklist.
+      const r = await fetch('/api/suggestions/blocklist', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ name }),
+      });
+      const j = await r.json();
+      if (!j.ok) {
+        chip.dataset.disabled = 'false';
+        chip.style.pointerEvents = '';
+        if (tagActionFeedback) tagActionFeedback.textContent = `Couldn't blocklist: ${j.error || 'error'}`;
+        return;
+      }
+      // Also log a rejection for this image so the ML feedback signal is
+      // captured — the user rejected this specific suggestion too.
+      try {
+        await fetch(`/image/${imageId}/suggestions/reject`, {
+          method: 'POST',
+          headers: { 'Content-Type': 'application/json' },
+          body: JSON.stringify({
+            tag_name: name,
+            source: chip.dataset.source || '',
+            confidence: Number(chip.dataset.confidence) || 0,
+          }),
+        });
+      } catch {
+        // best-effort — blocklist succeeded is what matters
+      }
+      if (tagActionFeedback) tagActionFeedback.textContent = `Blocklisted '${name}'`;
+      // Remove every chip on the page with this name so the user doesn't have to
+      // dismiss the same suggestion once per category.
+      document.querySelectorAll('.suggestion-chip').forEach(el => {
+        if (el.dataset.tagName === name) animateChipOut(el);
+      });
+    } catch {
+      chip.dataset.disabled = 'false';
+      chip.style.pointerEvents = '';
+    }
+  }
+
   function renderSuggestions(grouped, imageId) {
     if (!suggestionsSection || !suggestionsList) return;
     suggestionsList.innerHTML = '';