redact: UX overhaul — engine simplification, credits, spinner, save-to-docs, badges

- Remove GPU/regex engine options; keep only azure_mini (1 credit) and azure_full (2 credits)
- Variable credit cost: engine-aware pre-check and charge in api/redact.php; PricingCatalog base = 1
- Fix ATTORNEY not preserved when keepOfficials=true: add to LLM prompt, generic-tag, pseudonym regexes
- Replace Azure credits hint with per-engine credit cost text (all 4 languages)
- Single-file upload only (was: up to 5); simplify status messages
- Clear previous redaction output and show pulsing spinner when a new run starts
- Add "Save to My Docs" button in redact output panel (corpus-save.js path)
- corpus-save.js: capture source_doc_ids from button dataset, pass in POST payload
- api/save-to-corpus.php: accept source_doc_ids, store first as source_url=corpus-doc:{id}
- doc-picker.js: show "✂ Redacted" badge for documents saved from the redact tool
- CSS: .redact-working spinner, doc-item__badge--redact pill styles

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

assets/css/tools.css

@@ -2266,6 +2266,38 @@ p {
   cursor: progress;
 }
 
+@keyframes redact-spin {
+  to { transform: rotate(360deg); }
+}
+
+.redact-working {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  gap: 12px;
+  padding: 32px 16px;
+  border: 1px solid var(--line);
+  border-radius: 8px;
+  background: #fbfcfe;
+}
+
+.redact-working p {
+  margin: 0;
+  color: var(--muted);
+  font-size: 0.92rem;
+}
+
+.redact-working__spinner {
+  display: block;
+  width: 22px;
+  height: 22px;
+  border: 3px solid var(--line);
+  border-top-color: var(--teal);
+  border-radius: 50%;
+  animation: redact-spin 0.9s linear infinite;
+}
+
 /* ── Feedback widget ──────────────────────────────────────────── */
 .feedback-widget {
   margin-top: 1.5rem;