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/view/markdown.rs

@@ -1,6 +1,30 @@
+//! Markdown-to-styled-spans rendering for the chat transcript.
+//!
+//! Flow: `render_markdown` walks a `pulldown_cmark` event stream and
+//! translates each markdown construct (headings, code blocks, links,
+//! emphasis, block quotes, lists) into styled `ratatui::text::Span`s,
+//! then optionally re-wraps the flat span list to a target column width.
+//!
+//! Why: ratatui has no built-in markdown renderer, so this module bridges
+//! `pulldown_cmark`'s event-based parser to ratatui's span/line model.
+
 use ratatui::style::{Color, Modifier, Style};
 use ratatui::text::Span;
 
+/// Render a markdown string into styled terminal spans, word-wrapped to `width`.
+///
+/// Flow: pulldown_cmark parses `text` into an event stream → each
+/// Start/End/Text/Code/Break event is translated into styled `Span`s
+/// (headings colored by level, code blocks green, links bracketed, etc.)
+/// → if `width > 0`, a second pass inserts manual newline spans whenever
+/// the running line length would exceed `width`.
+///
+/// Why: ratatui has no native markdown renderer, and the built-in `Wrap`
+/// widget wraps on grapheme count without honoring markdown structure,
+/// so wrapping is done manually here in terms of raw span byte length.
+///
+/// Return: a flat vec of styled spans; `chat::split_spans_into_lines`
+/// turns it back into `Line`s for the Paragraph widget.
 pub fn render_markdown(text: &str, width: u16) -> Vec<Span<'static>> {
     let mut spans = Vec::new();
     let parser = pulldown_cmark::Parser::new(text);