Implement CYA-WP-0008 llm-connect adapter integration.

Wire LLMConnectAdapter behind the existing LLMAdapter seam with config-driven
selection, graceful degradation, --offline mode, and bounded session context.
Add unit tests, integration docs, and update README/SCOPE/AGENTS.

tests/test_llm_prompt.py

@@ -0,0 +1,22 @@
+"""Prompt builder tests."""
+
+from cya.llm.adapter import AssistanceRequest
+from cya.llm.prompt import build_assistance_prompt
+
+
+def test_build_assistance_prompt_includes_context_and_request():
+    system, user = build_assistance_prompt(
+        AssistanceRequest(
+            user_request="list files",
+            context={
+                "cwd": "/home/user/proj",
+                "session_turns": [{"user": "hi", "assistant": "hello"}],
+                "memory": {"items": [{"kind": "preference", "key": "style", "value": "concise"}]},
+            },
+        )
+    )
+    assert "cya" in system.lower()
+    assert "list files" in user
+    assert "/home/user/proj" in user
+    assert "hi" in user
+    assert "concise" in user