fix(stop): the exit-4 refusal names where the holder may be (Issue #31, Mac review)

The refusal pointed at ~/.claude/sessions/ for every agent, whatever
CLAUDE_CONFIG_DIR said, and never mentioned a non-agent process naming the
uuid on its command line. The in-use CLI now prints, on stderr while the
conversation is in use, the adapter's in_use_hints: for every adapter
`ps -axww | grep <uuid>`, and for claude its real sessions/ dir first. stop
prints them under its refusal, and says "records preserved" instead of
"no state was modified": the gate runs after the kill chain, so the session
itself may already be down. SKILL.md's exit 4 row says the same; it is not
a code block, so no inventory hash moves.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.agents/skills/lib_py/agents/adapters/claude.py

@@ -345,6 +345,10 @@ class ClaudeAgentAdapter(BaseAgentAdapter):
             return True
         return any(_session_file_live(data, pid) for _, pid, data in self._session_files(uuid, ctx))
 
+    def in_use_hints(self, uuid: str, ctx: DiscoveryContext) -> list:
+        return [f"a claude process whose session file under {os.path.join(_config_dir(ctx), 'sessions')}/ names it"] \
+            + super().in_use_hints(uuid, ctx)
+
     def purge_artifacts(self, uuid: str, ctx: DiscoveryContext) -> list:
         # Best effort: never raises (stop runs this inside its registry
         # transaction). What could not be removed is not listed here and