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/mod.rs

@@ -1,3 +1,6 @@
+//! TUI mode definitions and per-mode input/action handlers, one submodule
+//! per overlay/mode (bash, editor, effort, mcp, quit confirm, rewind, etc.).
+
 use serde::{Deserialize, Serialize};
 
 pub mod bash;
@@ -11,6 +14,8 @@ pub mod rewind;
 pub mod settings;
 pub mod todo;
 
+/// Which input/overlay mode the TUI is currently in; drives both key
+/// routing (`controller/input.rs`) and rendering.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
 pub enum ModeKind {
     Chat,