init: seed framework reference content from agent-runtimes main repo

harnesses/composites/code-airouter-repo/v1/harness.yaml

@@ -0,0 +1,11 @@
+kind: composite
+name: code-airouter-repo
+version: 1
+description: "Code agent with Airouter Qwen3.6 + repo clone via SSH"
+
+layers:
+  - context: qwen-code-methodology/v1
+  - context: best-practices/v1
+  - context: airouter/v1
+  - context: gitea-ssh/v1
+  - context: agent-repo/v1