rename agent: fix tool calls and target override

- Add memory_rename tool (in-place rename, preserves content and links)
- Update rename.agent prompt to use memory_rename() instead of text output
- Fix {{rename}} placeholder to respect --target keys when provided
- Add format_rename_targets() for targeted rename runs

src/subconscious/defs.rs

@@ -237,8 +237,14 @@ fn resolve(
         }
 
         "rename" => {
-            let (rename_keys, section) = super::prompts::format_rename_candidates(store, count);
-            Some(Resolved { text: section, keys: rename_keys })
+            if !keys.is_empty() {
+                // --target provided: present those keys as candidates
+                let section = super::prompts::format_rename_targets(store, keys);
+                Some(Resolved { text: section, keys: vec![] })
+            } else {
+                let (rename_keys, section) = super::prompts::format_rename_candidates(store, count);
+                Some(Resolved { text: section, keys: rename_keys })
+            }
         }
 
         "split" => {