feat: conformance scenarios (core-01..core-09)

Declarative conformance scenarios for aicc/0.1 covering: handshake,
manifest_request, tool call ok/unknown/execution-failed, protocol
mismatch, heartbeat, session close, event delivery. Plus runner
documentation (conformance/README.md).

conformance/scenarios/core-01-handshake.json

@@ -0,0 +1,21 @@
+{
+  "id": "core-01-handshake",
+  "title": "Handshake: bridge sends a valid session_init",
+  "category": "core",
+  "version": "aicc/0.1",
+  "description": "On connect, the bridge must push a session_init message with a valid envelope and manifest structure.",
+  "steps": [
+    {
+      "expect": {
+        "type": "session_init",
+        "protocol": "aicc/0.1",
+        "session_id": {"$kind": "uuid"},
+        "tick_rate_hz": {"$gt": 0},
+        "tick_mode": {"$enum": ["fixed", "event", "hybrid"]},
+        "world": {"$required": ["name", "kind"]},
+        "capabilities": {"$required": ["sensors", "actuators", "generators"]},
+        "tools": {"$kind": "array"}
+      }
+    }
+  ]
+}