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/blobs.rs

@@ -1,6 +1,15 @@
+//! Binary blob storage in the message-log SQLite database (e.g. images,
+//! attachments), keyed by session id and an arbitrary blob key.
+
 use rusqlite::{Connection, params};
 use anyhow::Result;
 
+/// Insert or overwrite a blob for a session under `blob_key`.
+///
+/// Flow: compute current timestamp → `INSERT OR REPLACE` into `blobs`
+/// keyed on `(session_id, blob_key)`.
+///
+/// Return: `Ok(())` on success, or the underlying SQLite error.
 pub fn store_blob(conn: &Connection, session_id: &str, blob_key: &str, data: &[u8], mime_type: Option<&str>) -> Result<()> {
     let created_at = chrono::Utc::now().timestamp_millis();
     conn.execute(
@@ -10,6 +19,10 @@ pub fn store_blob(conn: &Connection, session_id: &str, blob_key: &str, data: &[u
     Ok(())
 }
 
+/// Fetch a blob's bytes for a session by key.
+///
+/// Return: `Ok(Some(data))` if found, `Ok(None)` if no matching row
+/// exists, `Err` for any other SQLite failure.
 pub fn retrieve_blob(conn: &Connection, session_id: &str, blob_key: &str) -> Result<Option<Vec<u8>>> {
     let result = conn.query_row(
         "SELECT data FROM blobs WHERE session_id = ?1 AND blob_key = ?2",
@@ -23,6 +36,10 @@ pub fn retrieve_blob(conn: &Connection, session_id: &str, blob_key: &str) -> Res
     }
 }
 
+/// Delete a blob for a session by key.
+///
+/// Return: `Ok(true)` if a row was deleted, `Ok(false)` if no matching
+/// row existed.
 #[allow(dead_code)]
 pub fn delete_blob(conn: &Connection, session_id: &str, blob_key: &str) -> Result<bool> {
     let rows = conn.execute(
@@ -32,6 +49,10 @@ pub fn delete_blob(conn: &Connection, session_id: &str, blob_key: &str) -> Resul
     Ok(rows > 0)
 }
 
+/// List all blob keys stored for a session, oldest first.
+///
+/// Return: `Ok(Vec<String>)` of keys ordered by `created_at`, or the
+/// underlying SQLite error.
 pub fn list_blob_keys(conn: &Connection, session_id: &str) -> Result<Vec<String>> {
     let mut stmt = conn.prepare(
         "SELECT blob_key FROM blobs WHERE session_id = ?1 ORDER BY created_at ASC"