fix(api,watcher): name the queue, list parked non-markdown, reserved wings, top-level-only frontmatter key; document the inbox (review of #211)

- brain_promote/brain_reject take an optional queue (inbox | needs-review); a
  name present in both is refused instead of silently acting on the top-level
  note; brain_pending labels every entry with its queue
- parked pdf/txt files are listed (they were invisible); only markdown can be
  promoted, the others are moved or rejected
- promote refuses sources/concepts/entities/wiki as a wing
- frontmatterWing reads only a top-level key inside a properly fenced block
- docs/raw-inbox.md: the contract, the three env vars, the known limits
Each behaviour has a test that fails without it (mutation-checked).

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

docs/raw-inbox.md

@@ -0,0 +1,49 @@
+# The raw/ inbox
+
+`raw/` is an inbox: only unprocessed material sits there. Syncthing shares it
+with the machines you drop files from. (hyperguild#205, #208, #209)
+
+## What happens to a file you drop
+
+| You drop | Result |
+|---|---|
+| `raw/clip.md` (no folder, no `wing:`) | extracted and filed as a source in `wiki/web-clip/sources/`; its concepts and entities update the shared `wiki/concepts/` and `wiki/entities/` pages; the original moves to `raw/processed/<date>/`, so `raw/` is empty again |
+| `raw/<wing>/clip.md` or `wing: <wing>` in the frontmatter | the same, with the source in `wiki/<wing>/sources/`. The wing must already exist; a typo is parked, never created. This is your deliberate choice and is not second-guessed |
+| a note whose text matches the client-content pattern, with no folder | parked in `raw/needs-review/`, not extracted |
+| a folder or `wing:` naming an unknown, reserved or non-ASCII wing, or two disagreeing signals | parked in `raw/needs-review/` |
+| a note over the size cap, or one that cannot be archived | stays in `raw/`, reported once, not retried until it changes |
+
+Concepts and entities are shared across wings because their slug is the graph's
+identity. A source whose slug is taken gets a wing-qualified one (`notes-homelab`).
+
+## Parked notes
+
+`brain_pending` lists them with `queue: needs-review`, a proposed wing and the
+reason. To act on one: `brain_promote` / `brain_reject` (pass `queue` when the
+same name also sits in the inbox), or move the file into `raw/<wing>/` to have it
+extracted. Parked pdf/txt files are listed but can only be moved or rejected.
+
+## Switching it on
+
+Routing is off by default (the retired layout is used). Set on the ingestion
+deployment:
+
+| Variable | Meaning |
+|---|---|
+| `INGEST_WING_ROUTING=1` | enable the rules above |
+| `INGEST_DEFAULT_WING` | wing for unsignalled notes (default `web-clip`; must be a plain name, not `sources`/`concepts`/`entities`/`wiki`) |
+| `INGEST_CLIENT_BLOCK` | case-insensitive regexp over note text; a match parks an unsignalled note. Falls back to `CLAUDE_INGEST_CLIENT_BLOCK`. Matched after folding fullwidth letters, removing zero-width characters, normalising dashes and removing whitespace. It catches what it names and nothing else |
+
+A bad default or pattern stops the server at startup. A wing created while the
+server runs is usable without a restart.
+
+## Known limits
+
+- A deliberate folder into a sensitive wing places the note there, and the shared
+  concept/entity pages then cite that source by title. Client material does not
+  belong in the brain at all; the pattern only guards the unsignalled lane.
+- A merge into a shared page refreshes `last_updated` and `origin` to the latest
+  ingest; the first wing's attribution is not kept.
+- A marker file (`<note>.processed`) is only written when a processed original
+  cannot be removed. One at least as new as its note holds the note (and says
+  so once); an older or future-dated one is ignored and removed.