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/mcp/handlers_test.go

@@ -431,3 +431,28 @@ func TestBrainRejectMissingSourceErrors(t *testing.T) {
 	resp := toolCall(t, srv, "brain_reject", map[string]any{"filename": "ghost.md"})
 	require.NotNil(t, resp["error"])
 }
+
+// brain_pending lists two entries for one name when a top-level note and a
+// parked one share it; the tool must let the caller say which it means.
+func TestBrainPromoteAndRejectTakeTheQueueOfAnAmbiguousName(t *testing.T) {
+	brainDir := t.TempDir()
+	raw := filepath.Join(brainDir, "raw")
+	require.NoError(t, os.MkdirAll(filepath.Join(raw, "needs-review"), 0o755))
+	require.NoError(t, os.WriteFile(filepath.Join(raw, "a.md"), []byte("---\ncreated_at: 2026-10-20T00:00:00Z\n---\nTOP\n"), 0o644))
+	require.NoError(t, os.WriteFile(filepath.Join(raw, "needs-review", "a.md"), []byte("---\nproposed_wing: homelab\n---\nPARKED\n"), 0o644))
+	srv := mcp.NewServer(brainDir, nil, nil, nil)
+
+	resp := toolCall(t, srv, "brain_promote", map[string]any{"filename": "a.md", "wing": "homelab", "hall": "facts"})
+	require.NotNil(t, resp["error"], "an ambiguous name is refused, not guessed")
+
+	resp = toolCall(t, srv, "brain_promote", map[string]any{"filename": "a.md", "wing": "homelab", "hall": "facts", "queue": "needs-review"})
+	require.Nil(t, resp["error"], "got: %v", resp["error"])
+	got, err := os.ReadFile(filepath.Join(brainDir, "wiki/homelab/facts/a.md"))
+	require.NoError(t, err)
+	assert.Contains(t, string(got), "PARKED")
+
+	resp = toolCall(t, srv, "brain_reject", map[string]any{"filename": "a.md", "queue": "inbox", "reason": "no"})
+	require.Nil(t, resp["error"], "got: %v", resp["error"])
+	_, err = os.Stat(filepath.Join(brainDir, "raw/rejected/a.md"))
+	assert.NoError(t, err)
+}