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/pages/admin/settings/knowledgebases/(data)/index-state-marks.ts

@@ -0,0 +1,33 @@
+import { CircleAlert, CircleCheck, LoaderCircle, TriangleAlert, type LucideIcon } from "lucide-react";
+import type { KnowledgebaseIndexState } from "@/src/utils/knowledgebase-index-state";
+
+/**
+ * The mark beside a knowledgebase or document for each index state, and
+ * what it says on hover. Green only when bots search all of it by meaning.
+ */
+export const IndexStateMarks: Record<
+    Exclude<KnowledgebaseIndexState, "empty">,
+    { Icon: LucideIcon; label: string; className: string[] }
+> = {
+    indexing: { Icon: LoaderCircle, label: "Being read", className: ["animate-spin", "text-ink-secondary"] },
+    failed: {
+        Icon: TriangleAlert,
+        label: "Something couldn't be read",
+        className: ["text-warning", "dark:text-warning-dark"],
+    },
+    words: {
+        Icon: CircleCheck,
+        label: "Read, found by words only: no embedding model is set",
+        className: ["text-ink-disabled"],
+    },
+    stale: {
+        Icon: CircleAlert,
+        label: "Read with another embedding model: needs re-indexing",
+        className: ["text-ink-disabled"],
+    },
+    indexed: {
+        Icon: CircleCheck,
+        label: "Indexed: bots search all of it by meaning",
+        className: ["text-success", "dark:text-success-dark"],
+    },
+};