cleanup: remove dead placeholder code, use RPC for identity loading

- links() in memory.rs: use cached_store() instead of MemoryNode::load()
- identity.rs: use memory_rpc for Store context loading
- defs.rs: delete dead placeholders (topology, nodes/episodes, health, split)
  - agents now use {{tool: graph_topology}} etc instead
- prompts.rs: delete unused format_split_plan_node()

Co-Authored-By: Kent Overstreet <kent.overstreet@linux.dev>

src/subconscious/defs.rs

@@ -208,24 +208,6 @@ fn resolve(
     count: usize,
 ) -> Option<Resolved> {
     match name {
-        "topology" => Some(Resolved {
-            text: super::prompts::format_topology_header(store, graph),
-            keys: vec![],
-        }),
-
-        "nodes" | "episodes" => {
-            let items = keys_to_replay_items(store, keys, graph);
-            Some(Resolved {
-                text: super::prompts::format_nodes_section(store, &items, graph),
-                keys: vec![], // keys already tracked from query
-            })
-        }
-
-        "health" => Some(Resolved {
-            text: super::prompts::format_health_section(store, graph),
-            keys: vec![],
-        }),
-
         "rename" => {
             if !keys.is_empty() {
                 // --target provided: present those keys as candidates
@@ -237,14 +219,6 @@ fn resolve(
             }
         }
 
-        "split" => {
-            let key = keys.first()?;
-            Some(Resolved {
-                text: super::prompts::format_split_plan_node(store, graph, key),
-                keys: vec![], // key already tracked from query
-            })
-        }
-
         // seed — render output for each seed node (content + deduped links)
         "seed" => {
             let mut text = String::new();