fix(ai): stop RAG coverage bar sticking below 100% on empty pages

"Indexed N of M pages" stayed at e.g. "27 of 34" forever even after a
successful full reindex. The numerator counted pages that have embeddings
while the denominator counted ALL non-deleted pages, so empty / text-less
pages (which legitimately store zero embeddings) could never be reached.

Add PageRepo.countEmbeddablePages: counts non-deleted pages that have
non-empty textContent OR already have a stored embedding row, and use it as
the totalPages denominator in AiSettingsService.getMasked. The "has
embeddings" clause covers pages indexed from the content JSON (null
textContent) and guarantees indexedPages <= totalPages. No DB migration.

apps/server/src/integrations/ai/ai-settings.service.ts

@@ -160,9 +160,12 @@ export class AiSettingsService {
       hasEmbeddingApiKey = !!creds?.embeddingApiKeyEnc;
     }
 
+    // totalPages now counts only pages with embeddable content (non-empty text
+    // or already-stored embeddings), so empty/text-less pages don't keep the
+    // "Indexed N of M pages" bar below 100% forever.
     const [indexedPages, totalPages] = await Promise.all([
       this.pageEmbeddingRepo.countIndexedPages(workspaceId),
-      this.pageRepo.countByWorkspace(workspaceId),
+      this.pageRepo.countEmbeddablePages(workspaceId),
     ]);
 
     return {