Enhance tool documentation and add new features

- Added module-level documentation for memory tools (`remember`, `recall`, `forget`) to clarify their purpose.
- Improved documentation in `recall.rs` and `remember.rs` to describe the functionality and flow of memory entry operations.
- Updated `mod.rs` to include descriptions for the tool trait and execution context.
- Enhanced `plan.rs` with detailed comments on plan-mode signaling tools.
- Documented text search tools in `search.rs` to explain their functionality.
- Improved sequential-thinking tool documentation in `seqthink.rs`.
- Added safety filter documentation in `shell_filter` for credential and git operations.
- Enhanced utility tools documentation, including `cd`, `dir_cache_update`, and `todowrite`.
- Improved rendering documentation in view modules (`chat`, `markdown`, `status`, `workflow`) to clarify rendering flows and purposes.

src/app/mode/key_input.rs

@@ -1,5 +1,8 @@
+//! Key input mode: raw text capture overlay used for one-off key/text prompts.
+
 use crate::app::state::rest::AppStateRest;
 
+/// Replace the input buffer with the given text and mark state dirty.
 pub fn handle_key_text(state: &mut AppStateRest, text: String) {
     state.input.buffer = text;
     state.dirty = true;