fix: exclude current session from session_search results

session_search was returning the current session if it matched the
query, which is redundant — the agent already has the current
conversation context. This wasted an LLM summarization call and a
result slot.

Added current_session_id parameter to session_search(). The agent
passes self.session_id and the search filters out any results where
either the raw or parent-resolved session ID matches. Both the raw
match and the parent-resolved match are checked to handle child
sessions from delegation.

Two tests added verifying the exclusion works and that other
sessions are still returned.

run_agent.py

@@ -2476,6 +2476,7 @@ class AIAgent:
                         role_filter=function_args.get("role_filter"),
                         limit=function_args.get("limit", 3),
                         db=self._session_db,
+                        current_session_id=self.session_id,
                     )
                 tool_duration = time.time() - tool_start_time
                 if self.quiet_mode: