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/dto/chat/message.rs

@@ -1,5 +1,9 @@
+//! Chat message types shared across the DTO layer: `Role` and `ChatMessage`
+//! with convenience constructors.
+
 use serde::{Deserialize, Serialize};
 
+/// The conversation participant who authored a message.
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub enum Role {
     #[serde(rename = "user")]
@@ -15,6 +19,8 @@ pub enum Role {
 impl Role {
 }
 
+/// A single message in a conversation, compatible with the OpenAI/Anthropic
+/// chat-completion API structures.
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct ChatMessage {
     pub role: Role,
@@ -28,6 +34,7 @@ pub struct ChatMessage {
 }
 
 impl ChatMessage {
+    /// Build a user-role message with the given text content.
     pub fn user(content: impl Into<String>) -> Self {
         ChatMessage {
             role: Role::User,
@@ -38,6 +45,7 @@ impl ChatMessage {
         }
     }
 
+    /// Build an assistant-role message with an optional text response.
     pub fn assistant(content: Option<String>) -> Self {
         ChatMessage {
             role: Role::Assistant,
@@ -48,6 +56,7 @@ impl ChatMessage {
         }
     }
 
+    /// Build a system-role message with the given instruction text.
     pub fn system(content: impl Into<String>) -> Self {
         ChatMessage {
             role: Role::System,
@@ -58,6 +67,7 @@ impl ChatMessage {
         }
     }
 
+    /// Build a tool-role result message referencing a prior tool call.
     pub fn tool_result(tool_call_id: String, content: String) -> Self {
         ChatMessage {
             role: Role::Tool,