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.

src/cya/llm/prompt.py

@@ -0,0 +1,73 @@
+"""Prompt construction for llm-connect delegation (CYA-WP-0008)."""
+
+from __future__ import annotations
+
+import json
+from typing import Any
+
+from cya.llm.adapter import AssistanceRequest
+
+_DEFAULT_SYSTEM = """You are cya, a console-native assistant for practical local work from the shell.
+
+Help the user with command-line tasks: repository inspection, file workflows, command
+suggestion, command explanation, and local context summarization.
+
+Be concise and practical. When suggesting shell commands, explain risks briefly.
+Do not claim to have executed anything — the user runs commands themselves.
+Reference the provided context when it is relevant."""
+
+
+def default_system_prompt() -> str:
+    return _DEFAULT_SYSTEM
+
+
+def build_assistance_prompt(request: AssistanceRequest, *, system_prompt: str | None = None) -> tuple[str, str]:
+    """Return (system_prompt, user_prompt) for llm-connect execute_prompt."""
+    system = system_prompt or default_system_prompt()
+    parts: list[str] = []
+
+    context = request.context or {}
+    session_turns = context.get("session_turns")
+    if session_turns:
+        parts.append("## Recent conversation")
+        for turn in session_turns:
+            parts.append(f"User: {turn.get('user', '')}")
+            parts.append(f"Assistant: {turn.get('assistant', '')}")
+
+    envelope = {k: v for k, v in context.items() if k not in ("session_turns", "memory")}
+    if envelope:
+        parts.append("## Local context")
+        parts.append(_summarize_context(envelope))
+
+    memory = context.get("memory")
+    if isinstance(memory, dict) and memory.get("items"):
+        parts.append("## Activated memory")
+        for item in memory["items"][:8]:
+            parts.append(f"- [{item.get('kind', '?')}] {item.get('key', '?')}: {item.get('value', '')}")
+
+    parts.append("## Current request")
+    parts.append(request.user_request.strip())
+
+    return system, "\n\n".join(parts)
+
+
+def _summarize_context(envelope: dict[str, Any]) -> str:
+    """Compact, JSON-safe context summary to stay within prompt budget."""
+    summary: dict[str, Any] = {}
+    if envelope.get("cwd"):
+        summary["cwd"] = envelope["cwd"]
+    if envelope.get("git"):
+        git = envelope["git"]
+        summary["git"] = {
+            k: git[k]
+            for k in ("branch", "status_short", "workdir", "is_repo")
+            if k in git
+        }
+    if envelope.get("top_level"):
+        names = [e.get("name") for e in envelope["top_level"][:30] if e.get("name")]
+        summary["top_level"] = names
+    if envelope.get("env"):
+        summary["env"] = envelope["env"]
+    if envelope.get("notes"):
+        summary["notes"] = envelope["notes"][:5]
+    return json.dumps(summary, indent=2, default=str)