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>

includes/PricingCatalog.php

@@ -133,7 +133,7 @@ final class PricingCatalog
             'translate' => 1,
             'korrespond_refine' => 1,
             'timeline' => 2,
-            'redact' => 2,
+            'redact' => 1, // minimum (gpt-4o-mini); azure_full overrides to 2 in api/redact.php
             'barnevernet' => 3,
             'advocate' => 3,
             'korrespond' => 3,