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>

ingestion/internal/api/handler.go

@@ -617,6 +617,7 @@ type promoteRequest struct {
 	Wing     string `json:"wing"`
 	Hall     string `json:"hall"`
 	Slug     string `json:"slug,omitempty"`
+	Queue    string `json:"queue,omitempty"`
 }
 
 // Promote handles POST /promote — move a raw/ note into the wiki. A bad
@@ -630,7 +631,7 @@ func (h *Handler) Promote(w http.ResponseWriter, r *http.Request) {
 	// Field by field: this door carries no principal, so the promoted note is
 	// stamped origin: unknown and the body cannot set provenance (#145).
 	rel, err := PromoteNote(h.brainDir, PromoteOptions{
-		Filename: req.Filename, Wing: req.Wing, Hall: req.Hall, Slug: req.Slug,
+		Filename: req.Filename, Wing: req.Wing, Hall: req.Hall, Slug: req.Slug, Queue: req.Queue,
 	})
 	if err != nil {
 		writeError(w, http.StatusBadRequest, err.Error())