Add knowledgebases

Knowledgebases give bots RAG over documents, scoped like extensions: to
particular bots, to a workspace, or to every bot, with their own button
beside Tools in the composer. Documents are chunked and embedded by the
file-ingest worker with the install's embedding model, which is now an
install-wide setting rather than a per-bot one.

- Word search runs on an FTS5 index ranked by BM25, with a scored LIKE
  fallback for scripts written without spaces.
- Changing the embedding model re-indexes documents automatically.
- Ingest jobs wait without spending attempts while every embedding model
  rests, fail at once on errors retrying can't fix, and keep passages
  searchable by words when the model refuses.
- Settings > Knowledgebases shows each knowledgebase's and document's
  index state: spinner, warning, grey check (words only) or green check.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/cron/sync-harness-models/index.ts

@@ -1,14 +1,25 @@
 import syncAllHarnessModels from "@/src/functions/backend/db/harness/sync-all-harness-models";
+import grabInstallEmbeddingModel from "@/src/functions/backend/db/knowledgebases/grab-install-embedding-model";
+import reindexAfterEmbeddingChange from "@/src/functions/backend/db/knowledgebases/reindex-after-embedding-change";
 import { logError } from "@/src/functions/backend/logger";
 
 /**
  * Refreshes every enabled provider's model list. Free models on OpenRouter
  * come and go, and automatic picks follow them from this list. A provider
  * that fails doesn't fail the run, so its error goes to the logs here.
+ * When the refresh changes the install's embedding model (its pick left
+ * the catalog), knowledgebases are read again with the new one.
  */
 export default async function cronSyncHarnessModels() {
+    const embedding_before = await grabInstallEmbeddingModel();
     const results = await syncAllHarnessModels();
 
+    await reindexAfterEmbeddingChange({ before: embedding_before }).catch((error) =>
+        logError({ title: "Cron: knowledgebase re-index after a model change failed", category: "cron", error }).catch(
+            () => {},
+        ),
+    );
+
     for (const result of results) {
         if (!result.error) continue;