Adds a persistent state machine for AI knowledge-base ingestion so the
scanner can distinguish "fully indexed", "user opted out", "failed", and
"stalled" from each other — none of which were derivable from the prior
binary "any chunks in Qdrant ⇒ embedded" check.
## What lands
- New table `kb_ingest_state` keyed by `file_path` with enum state column
(`pending_decision | indexed | browse_only | failed | stalled`).
Independent of `installed_resources` so it covers both curated downloads
and manually-uploaded KB files.
- New KV key `rag.defaultIngestPolicy` (string: `Always | Manual`).
Registered now but not consumed yet — JIT prompt + wizard step land in
Phase 3 of the RFC.
- `EmbedFileJob.handle` writes state on terminal outcomes:
- Success (final batch) → `indexed` + chunks count
- `UnrecoverableError` → `failed` + error message
- Retryable errors are left to BullMQ's existing retry path
- `scanAndSyncStorage` swaps the binary qdrant check for a state-aware
decision tree (see `decideScanAction`). Existing installs auto-backfill
on first scan: files with chunks in Qdrant but no state row become
`indexed`; new files start as `pending_decision`.
- `deleteFileBySource` drops the state row last, so removed files
disappear entirely instead of leaving an orphan that the next scan
would re-dispatch into nothing.
## What does NOT land here
- Ratio registry (separate PR) — needed for partial-stall detection and
cost estimates, but a separable concern.
- #880 follow-up initial-progress anchor (separate tiny PR).
- Phase 2 UI (status pill, per-card actions, conditional warnings).
- Phase 3 policy surfaces (wizard step, JIT prompt, guardrail modal).
- PR #886's bulk-action hookup — `_deletePointsBySource` / Re-embed All
/ Reset & Rebuild would also want to set state, but #886 isn't merged
yet; that wiring goes in a follow-up once #886 lands.
## Target
This is forward work for v1.40.0 (RFC #883). Branching off `rc` because
that's the current latest base and post-GA Jake will sync rc→dev; a
retarget at PR-open time is a fast-forward if requested.
## Tests
- 9 new unit tests for `decideScanAction` covering all five states plus
the no-row / chunks-present / chunks-missing combinations
- Type-check clean
- Smoke-tested end-to-end on NOMAD3 via hot-patch:
- Backfill: 5 ZIMs + 2 KB uploads with existing chunks in Qdrant all
came back `indexed` on first scan
- Pending dispatch: a video-only ZIM with no chunks (`lrnselfreliance`)
came back `pending_decision` and was correctly re-dispatched (Bull
deduped to its historical `:completed` jobId — bgauger's #886 fix
drains that)
- Delete hook: deleting a KB upload via `DELETE /api/rag/files`
removed both the disk file and the state row
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