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/promote_review_test.go

@@ -48,19 +48,6 @@ func TestRejectNote_ActsOnANoteParkedInNeedsReview(t *testing.T) {
 	assert.Empty(t, pending, "a rejected note is not re-listed")
 }
 
-func TestPromoteNote_ATopLevelNoteWinsOverAParkedOneOfTheSameName(t *testing.T) {
-	dir := t.TempDir()
-	writeRaw(t, dir, "same.md", "---\ncreated_at: 2026-10-20T08:00:00Z\n---\nTop-level body.\n")
-	writeParked(t, dir, "same.md", parkedNote)
-
-	_, err := PromoteNote(dir, PromoteOptions{Filename: "same.md", Wing: "homelab", Hall: "facts"})
-	require.NoError(t, err)
-	got, _ := os.ReadFile(filepath.Join(dir, "wiki/homelab/facts/same.md"))
-	assert.Contains(t, string(got), "Top-level body.")
-	_, statErr := os.Stat(filepath.Join(dir, "raw", "needs-review", "same.md"))
-	assert.NoError(t, statErr, "the parked note of the same name is left alone")
-}
-
 func TestPromoteNote_ASymlinkedNeedsReviewIsNotRead(t *testing.T) {
 	dir := t.TempDir()
 	outside := t.TempDir()