docs: point consumers to adapter seam / 文件明確導向 adapter seam

INSTALL.md

@@ -36,6 +36,13 @@ This does two things:
 
 ## Manual paths
 
+If you are extending the feature rather than merely applying the PoC, prefer starting from these repo-side integration seams before editing runtime files directly:
+
+- `src/adapters/openclaw-plugin-skeleton.ts`
+- `src/adapters/openclaw-interactive-handler.ts`
+- `src/adapters/openclaw-message-tool.ts`
+- `src/adapters/openclaw-state-file.ts`
+
 ### Apply patch only
 
 ```bash