Move agent queries inline: {{nodes}} → {{tool: memory_query}}

Add "format": "full" option to memory_query that renders with
full content, graph metrics, and hub analysis (format_nodes_section).
Convert 6 agents (linker, challenger, connector, extractor, replay,
transfer) to inline their queries via {{tool: memory_query}} instead
of separate header query + {{nodes}} placeholder.

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

src/subconscious/defs.rs

@@ -845,7 +845,7 @@ pub fn run_agent(
 }
 
 /// Convert a list of keys to ReplayItems with priority and graph metrics.
-fn keys_to_replay_items(
+pub fn keys_to_replay_items(
     store: &Store,
     keys: &[String],
     graph: &Graph,