feat: config-driven architecture, install wizard, live runtime switching, usage tracking, auto-failover

Major changes:
- Config-driven adapters: all channels (Slack, Discord, Telegram, WebChat, Webhooks) controlled via config.json with enabled flags and token auto-detection, no CLI flags required
- Runtime engine field: runtime.engine selects opencode/claude from config
- Interactive install script: 8-phase setup wizard with AI runtime detection/installation, token setup, identity file personalization (personality presets), aetheel CLI command, background service (launchd/systemd)
- Live runtime switching: /engine, /model, /provider commands hot-swap the AI runtime from chat without restart, changes persisted to config.json
- Usage tracking: per-request cost extraction from Claude Code JSON output, cumulative stats via /usage command
- Auto-failover: rate limit detection on both runtimes, automatic switch to other engine on quota errors with user notification
- Chat commands work without / prefix (Slack intercepts / in channels), commands: engine, model, provider, config, usage, reload, cron, subagents, status, help
- /config set for editing config.json from chat with dotted key notation
- Security audit saved to docs/security-audit.md
- Full command reference in docs/commands.md
- Future changes doc with NanoClaw agent teams analysis
- Logo added to README and WebChat UI
- README fully rewritten with all features documented

tests/test_subagent_bus.py

@@ -0,0 +1,122 @@
+"""
+Tests for SubagentBus pub/sub message bus.
+"""
+
+import threading
+
+import pytest
+
+from agent.subagent import SubagentBus, SubagentManager
+
+
+# ---------------------------------------------------------------------------
+# Fixtures
+# ---------------------------------------------------------------------------
+
+
+@pytest.fixture
+def bus():
+    return SubagentBus()
+
+
+# ---------------------------------------------------------------------------
+# Tests: SubagentBus
+# ---------------------------------------------------------------------------
+
+
+class TestSubagentBus:
+    def test_subscribe_and_publish(self, bus):
+        received = []
+        bus.subscribe("ch1", lambda msg, sender: received.append((msg, sender)))
+        bus.publish("ch1", "hello", "agent-1")
+        assert received == [("hello", "agent-1")]
+
+    def test_multiple_subscribers(self, bus):
+        received = []
+        bus.subscribe("ch1", lambda msg, sender: received.append(("a", msg)))
+        bus.subscribe("ch1", lambda msg, sender: received.append(("b", msg)))
+        bus.publish("ch1", "ping", "sender")
+        assert len(received) == 2
+        assert ("a", "ping") in received
+        assert ("b", "ping") in received
+
+    def test_publish_to_empty_channel(self, bus):
+        # Should not raise
+        bus.publish("nonexistent", "msg", "sender")
+
+    def test_unsubscribe_all(self, bus):
+        received = []
+        bus.subscribe("ch1", lambda msg, sender: received.append(msg))
+        bus.unsubscribe_all("ch1")
+        bus.publish("ch1", "hello", "sender")
+        assert received == []
+
+    def test_unsubscribe_all_nonexistent_channel(self, bus):
+        # Should not raise
+        bus.unsubscribe_all("nonexistent")
+
+    def test_channels_are_isolated(self, bus):
+        received_a = []
+        received_b = []
+        bus.subscribe("a", lambda msg, sender: received_a.append(msg))
+        bus.subscribe("b", lambda msg, sender: received_b.append(msg))
+        bus.publish("a", "only-a", "sender")
+        assert received_a == ["only-a"]
+        assert received_b == []
+
+    def test_callback_error_does_not_stop_others(self, bus):
+        received = []
+
+        def bad_cb(msg, sender):
+            raise RuntimeError("boom")
+
+        bus.subscribe("ch1", bad_cb)
+        bus.subscribe("ch1", lambda msg, sender: received.append(msg))
+        bus.publish("ch1", "hello", "sender")
+        # Second callback should still fire
+        assert received == ["hello"]
+
+    def test_thread_safety(self, bus):
+        """Concurrent subscribes and publishes should not crash."""
+        results = []
+        barrier = threading.Barrier(4)
+
+        def subscriber():
+            barrier.wait()
+            bus.subscribe("stress", lambda msg, sender: results.append(msg))
+
+        def publisher():
+            barrier.wait()
+            bus.publish("stress", "msg", "sender")
+
+        threads = [
+            threading.Thread(target=subscriber),
+            threading.Thread(target=subscriber),
+            threading.Thread(target=publisher),
+            threading.Thread(target=publisher),
+        ]
+        for t in threads:
+            t.start()
+        for t in threads:
+            t.join(timeout=5)
+
+
+# ---------------------------------------------------------------------------
+# Tests: SubagentManager.bus property
+# ---------------------------------------------------------------------------
+
+
+class TestSubagentManagerBus:
+    def test_manager_has_bus(self):
+        mgr = SubagentManager(
+            runtime_factory=lambda: None,
+            send_fn=lambda *a: None,
+        )
+        assert isinstance(mgr.bus, SubagentBus)
+
+    def test_bus_is_same_instance(self):
+        mgr = SubagentManager(
+            runtime_factory=lambda: None,
+            send_fn=lambda *a: None,
+        )
+        assert mgr.bus is mgr.bus