fix(ai): show live reindex progress in semantic-search settings

The "Indexed X of Y pages" counter stayed stuck at "478 of 478" during a
manual "Reindex now" run instead of resetting to 0 and climbing. The status
reports indexedPages = countIndexedPages (DISTINCT pages with >=1 embedding
row), but reindex hard-replaces each page in its OWN small transaction, so
nearly all pages always have rows -> the count never drops.

Add a per-workspace live reindex-progress record in Redis (reusing the
existing global ioredis client via RedisService, no new Redis config):
- EmbeddingReindexProgressService: start/increment/clear/get over a Redis hash
  with a 1h TTL self-clean; all best-effort/cosmetic so a Redis failure degrades
  to the existing DB-count behavior.
- AiSettingsService.reindex seeds {total, done:0, startedAt} at enqueue time so
  the very first poll already reports done=0.
- EmbeddingIndexerService.reindexWorkspace overwrites total with the real page
  count at start, increments done per processed page (success or handled
  failure), and clears the record in a finally (covers success, fatal abort,
  and the unconfigured early-return) so a failed run never sticks.
- AiSettingsService.getMasked returns the live run numbers when a progress
  record is active (plus an optional reindexing flag), else falls back to
  countIndexedPages/countEmbeddablePages.

Per-page edits (reindexPage) never touch the workspace progress record, and no
mass up-front delete is introduced (search availability preserved).

Tests: indexer sets/increments/clears progress (incl. fatal abort and
unconfigured early-return); status reports run progress when active and falls
back when not.

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

apps/server/src/integrations/ai/ai.module.ts

@@ -5,6 +5,7 @@ import { QueueName } from '../queue/constants';
 import { AiService } from './ai.service';
 import { AiSettingsService } from './ai-settings.service';
 import { AiSettingsController } from './ai-settings.controller';
+import { EmbeddingReindexProgressService } from './embedding-reindex-progress.service';
 
 /**
  * LLM driver + provider-settings unit (§6.2/§6.4).
@@ -19,7 +20,7 @@ import { AiSettingsController } from './ai-settings.controller';
     BullModule.registerQueue({ name: QueueName.AI_QUEUE }),
   ],
   controllers: [AiSettingsController],
-  providers: [AiService, AiSettingsService],
-  exports: [AiService, AiSettingsService],
+  providers: [AiService, AiSettingsService, EmbeddingReindexProgressService],
+  exports: [AiService, AiSettingsService, EmbeddingReindexProgressService],
 })
 export class AiModule {}