Add LSP rename (Phase 3) and update AGENTS.md with future work

- F2 keybinding triggers prepareRename at cursor
- Shows inline text input pre-filled with current symbol name
- Enter confirms and applies workspace edits across all occurrences
- Escape cancels the rename
- Full flow: prepareRename → input → rename → apply edits
- AGENTS.md: document inline token/cache/cost stats feature idea
- AGENTS.md: document rename implementation for reference

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/src/code/mod.rs

@@ -13,6 +13,8 @@ pub mod completion;
 #[cfg(not(target_family = "wasm"))]
 pub mod find_references_view;
 #[cfg(not(target_family = "wasm"))]
+pub mod rename;
+#[cfg(not(target_family = "wasm"))]
 pub mod signature_help;
 #[cfg(not(target_family = "wasm"))]
 pub mod language_server_extension;