feat: ML tag suggestions, character/fandom integrity, underscores, modal polish

Consolidated merge of feat/tag-suggestions branch. Original 64-commit history
was lost to git-object corruption in a Nextcloud-synced checkout; this single
commit captures the equivalent diff.

Includes:
- pgvector-backed tag suggestion infra (WD14 + SigLIP centroids, ml-worker
  container, Celery tasks, suggestion service, accept/reject endpoints + modal
  UI with green/red chip buttons)
- Character/fandom integrity: title-case normalization on every write path,
  fandom-id backfill, maintenance task + settings button, migrations g26041901
  + h26041901 to canonicalize legacy rows with case-only duplicate merging
- Tag-underscores + modal polish: WD14 name canonicalization at emit + accept
  + add/bulk-add paths, migration i26041901 for legacy-row rename-or-merge
  across character/fandom/NULL kinds, suggestion-accept refresh parity via
  awaited loadTags, persistent chip tint

app/static/style.css

@@ -840,6 +840,182 @@ header {
   color: #ef4444;
 }
 
+/* Modal provenance section — system-generated, non-editable tags (artist, post) */
+.modal-provenance-section {
+  border-bottom: none;
+}
+.modal-provenance-section .provenance-list {
+  display: flex;
+  flex-direction: column;
+  align-items: flex-start;
+  gap: 0.25rem;
+}
+
+.provenance-chip {
+  display: inline-flex;
+  align-items: center;
+  gap: 0.4rem;
+  padding: 2px 8px 2px 10px;
+  border-radius: 999px;
+  background: transparent;
+  color: var(--text-dim);
+  text-decoration: none;
+  border: 1px solid rgba(255, 255, 255, 0.15);
+  border-left-width: 2px;
+  border-left-color: rgba(255, 255, 255, 0.4);
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  font: 12px/1.6 system-ui, sans-serif;
+  max-width: clamp(8rem, 22vw, 14rem);
+  transition: border-color 0.15s ease, background 0.15s ease, color 0.15s ease;
+}
+
+.provenance-chip:hover {
+  border-color: rgba(255, 255, 255, 0.35);
+  background: rgba(255, 255, 255, 0.04);
+  color: var(--text);
+}
+
+.provenance-chip[data-platform="patreon"] {
+  border-left-color: #f96854;
+}
+.provenance-chip[data-platform="subscribestar"] {
+  border-left-color: #009cde;
+}
+.provenance-chip[data-platform="hentaifoundry"] {
+  border-left-color: #c8232c;
+}
+
+.provenance-chip .provenance-arrow {
+  opacity: 0.6;
+  font-size: 0.85em;
+}
+
+/* Modal suggestions section — ML-backed chips with accept/reject */
+.modal-suggestions-section .section-header {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  margin-bottom: 0.4rem;
+}
+.modal-suggestions-section .section-title {
+  font-size: 0.85rem;
+  font-weight: 600;
+  color: var(--text-dim);
+  letter-spacing: 0.04em;
+  text-transform: uppercase;
+}
+.modal-suggestions-section .suggestions-refresh {
+  background: transparent;
+  border: none;
+  color: var(--text-dim);
+  cursor: pointer;
+  font-size: 0.9rem;
+  padding: 0 0.25rem;
+}
+.modal-suggestions-section .suggestions-refresh:hover {
+  color: var(--text);
+}
+.suggestions-list {
+  display: flex;
+  flex-direction: column;
+  gap: 0.35rem;
+}
+.suggestions-category {
+  display: flex;
+  flex-direction: column;
+  gap: 0.2rem;
+}
+.suggestions-category-label {
+  font-size: 0.7rem;
+  color: var(--text-dim);
+  opacity: 0.65;
+  letter-spacing: 0.05em;
+  text-transform: uppercase;
+}
+.suggestions-chips {
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+}
+.suggestion-chip {
+  display: flex;
+  align-items: stretch;
+  gap: 6px;
+  min-height: 36px;
+  padding: 0;
+  border-radius: 6px;
+  background: rgba(255, 255, 255, 0.02);
+  color: var(--text-dim);
+  border: 1px dashed rgba(255, 255, 255, 0.18);
+  font: 13px/1.3 system-ui, sans-serif;
+  transition: border-color 0.15s ease, background 0.15s ease, color 0.15s ease, opacity 0.15s ease, transform 0.18s ease;
+}
+.suggestion-chip:hover {
+  border-color: rgba(255, 255, 255, 0.35);
+  background: rgba(255, 255, 255, 0.04);
+  color: var(--text);
+}
+.suggestion-chip .sugg-body {
+  flex: 1;
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  min-width: 0;
+  padding: 0 2px;
+}
+.suggestion-chip .sugg-label {
+  flex: 1;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+.suggestion-chip .sugg-confidence {
+  font-size: 0.72rem;
+  opacity: 0.6;
+  font-variant-numeric: tabular-nums;
+  flex-shrink: 0;
+}
+.suggestion-chip .sugg-btn {
+  flex: 0 0 auto;
+  width: 32px;
+  min-height: 32px;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  background: transparent;
+  border: 1px solid rgba(255, 255, 255, 0.15);
+  border-radius: 4px;
+  color: inherit;
+  cursor: pointer;
+  padding: 0;
+  font-size: 0.95rem;
+  line-height: 1;
+  margin: 1px;
+  transition: background 0.12s ease, color 0.12s ease, border-color 0.12s ease;
+}
+.suggestion-chip .sugg-btn.sugg-accept {
+  color: #8be78b;
+  border-color: rgba(139, 231, 139, 0.35);
+}
+.suggestion-chip .sugg-btn.sugg-accept:hover {
+  background: rgba(139, 231, 139, 0.12);
+  border-color: rgba(139, 231, 139, 0.6);
+}
+.suggestion-chip .sugg-btn.sugg-reject {
+  color: #e78b8b;
+  border-color: rgba(231, 139, 139, 0.35);
+}
+.suggestion-chip .sugg-btn.sugg-reject:hover {
+  background: rgba(231, 139, 139, 0.12);
+  border-color: rgba(231, 139, 139, 0.6);
+}
+.suggestion-chip.leaving {
+  opacity: 0;
+  transform: translateX(6px);
+}
+
 /* Tag form with autocomplete */
 .tag-form {
   display: flex;