fix: #169 — command-graph and tool-pool now accept --output-format; diagnostic inventory JSON parity

Extends the diagnostic surface audit with the two inventory-structure
commands: command-graph (command family segmentation) and tool-pool
(assembled tool inventory). Both now expose their underlying rich
datastructures via JSON envelope.

Concrete additions:
- command-graph: --output-format {text,json}
- tool-pool: --output-format {text,json}

JSON envelope shapes:

command-graph:
  {builtins_count, plugin_like_count, skill_like_count, total_count,
   builtins: [{name, source_hint}],
   plugin_like: [{name, source_hint}],
   skill_like: [{name, source_hint}]}

tool-pool:
  {simple_mode, include_mcp, tool_count,
   tools: [{name, source_hint}]}

Backward compatibility:
  - Default is 'text' (Markdown unchanged)
  - Text output byte-identical to pre-#169

Tests (4 new, test_command_graph_tool_pool_output_format.py):
  - TestCommandGraphOutputFormat (2): JSON structure + text compat
  - TestToolPoolOutputFormat (2): JSON structure + text compat

Full suite: 137 → 141 passing, zero regression.

Closes ROADMAP #169.

Why this matters:
  Claws auditing the codebase can now ask 'what commands exist' and
  'what tools exist' and get structured, parseable answers instead of
  regex-parsing Markdown headers and counting list items.

Related clusters:
  - Diagnostic surfaces (#169 adds to #167/#168 work-verb parity)
  - Inventory introspection (command-graph + tool-pool are the two
    foundational 'what do we have?' queries)

tests/test_command_graph_tool_pool_output_format.py

@@ -0,0 +1,70 @@
+"""Tests for --output-format on command-graph and tool-pool (ROADMAP #169).
+
+Diagnostic inventory surfaces now speak the CLI family's JSON contract.
+"""
+
+from __future__ import annotations
+
+import json
+import subprocess
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+
+def _run(args: list[str]) -> subprocess.CompletedProcess:
+    return subprocess.run(
+        [sys.executable, '-m', 'src.main', *args],
+        cwd=Path(__file__).resolve().parent.parent,
+        capture_output=True,
+        text=True,
+    )
+
+
+class TestCommandGraphOutputFormat:
+    def test_command_graph_json(self) -> None:
+        result = _run(['command-graph', '--output-format', 'json'])
+        assert result.returncode == 0, result.stderr
+
+        envelope = json.loads(result.stdout)
+        assert 'builtins_count' in envelope
+        assert 'plugin_like_count' in envelope
+        assert 'skill_like_count' in envelope
+        assert 'total_count' in envelope
+        assert envelope['total_count'] == (
+            envelope['builtins_count'] + envelope['plugin_like_count'] + envelope['skill_like_count']
+        )
+        assert isinstance(envelope['builtins'], list)
+        if envelope['builtins']:
+            assert set(envelope['builtins'][0].keys()) == {'name', 'source_hint'}
+
+    def test_command_graph_text_backward_compat(self) -> None:
+        result = _run(['command-graph'])
+        assert result.returncode == 0
+        assert '# Command Graph' in result.stdout
+        assert 'Builtins:' in result.stdout
+        # Not JSON
+        assert not result.stdout.strip().startswith('{')
+
+
+class TestToolPoolOutputFormat:
+    def test_tool_pool_json(self) -> None:
+        result = _run(['tool-pool', '--output-format', 'json'])
+        assert result.returncode == 0, result.stderr
+
+        envelope = json.loads(result.stdout)
+        assert 'simple_mode' in envelope
+        assert 'include_mcp' in envelope
+        assert 'tool_count' in envelope
+        assert 'tools' in envelope
+        assert envelope['tool_count'] == len(envelope['tools'])
+        if envelope['tools']:
+            assert set(envelope['tools'][0].keys()) == {'name', 'source_hint'}
+
+    def test_tool_pool_text_backward_compat(self) -> None:
+        result = _run(['tool-pool'])
+        assert result.returncode == 0
+        assert '# Tool Pool' in result.stdout
+        assert 'Simple mode:' in result.stdout
+        assert not result.stdout.strip().startswith('{')