feat(egress): add global log option for full request/response logging

Adds a top-level `log: true` option to the egress config that logs the
full request (method, path, headers, body) and response (status, headers,
body) for every forwarded connection as JSON lines on stderr.

Wire format: `log: true` at the root of routes.yaml, parsed into the new
`Config` dataclass alongside `routes`. The sidecar addon switches from
`self.routes` to `self.config` and writes `_log_request` / `_log_response`
JSON lines when `self.config.log` is set.

Manifest: `egress.log: true` in bottle YAML flows through `EgressConfig.Log`
→ `Egress.prepare()` → `egress_render_routes(..., log=)` → routes.yaml.
`EgressPlan` also carries the flag for introspection.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/unit/test_manifest_egress.py

@@ -346,6 +346,25 @@ class TestConfigShape(unittest.TestCase):
                                      "bottle": "dev"}},
             })
 
+    def test_log_defaults_false(self):
+        b = _bottle([])
+        self.assertFalse(b.egress.Log)
+
+    def test_log_true_accepted(self):
+        b = Manifest.from_json_obj({
+            "bottles": {"dev": {"egress": {"log": True, "routes": []}}},
+            "agents": {"demo": {"skills": [], "prompt": "", "bottle": "dev"}},
+        }).bottles["dev"]
+        self.assertTrue(b.egress.Log)
+
+    def test_log_non_bool_rejected(self):
+        with self.assertRaises(ManifestError):
+            Manifest.from_json_obj({
+                "bottles": {"dev": {"egress": {"log": "yes"}}},
+                "agents": {"demo": {"skills": [], "prompt": "",
+                                     "bottle": "dev"}},
+            })
+
 
 if __name__ == "__main__":
     unittest.main()