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/schema.rs

@@ -1,6 +1,15 @@
+//! SQLite schema definition for the message log database.
+
 use rusqlite::Connection;
 use anyhow::Result;
 
+/// Create the message log's tables and indexes if they don't already
+/// exist (`messages`, `archives`, `blobs`).
+///
+/// Why: idempotent via `CREATE TABLE/INDEX IF NOT EXISTS`, so it's safe
+/// to call on every `open_or_create`.
+///
+/// Return: `Ok(())` on success, or the underlying SQLite error.
 pub fn init_schema(conn: &Connection) -> Result<()> {
     conn.execute_batch(
         "