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/model/msglog/query.rs

@@ -1,7 +1,16 @@
+//! Insert queries against the message log's `messages` table.
+
 use rusqlite::{Connection, params};
 use anyhow::Result;
 use crate::dto::chat::message::{ChatMessage, Role};
 
+/// Insert a chat message into the session's message log.
+///
+/// Flow: extract optional content/tool_call_id/tool_name → serialize
+/// `tool_calls` to a JSON string if present → map `Role` to its string
+/// column value → `INSERT` the row with the current timestamp.
+///
+/// Return: the new row's `rowid` on success, or the underlying error.
 pub fn insert_message(conn: &Connection, session_id: &str, msg: &ChatMessage) -> Result<i64> {
     let content = msg.content.as_deref();
     let tool_call_id = msg.tool_call_id.as_deref();