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/tool.rs

@@ -1,6 +1,17 @@
+//! Tool-call DTOs embedded in assistant chat messages.
+//!
+//! Flow: provider response/stream carries `tool_calls` on an assistant
+//! message → deserialized into `ToolCall`/`ToolFunction` → harness resolves
+//! `function.name` against `all_tools()` and runs it with
+//! `sanitize_tool_arguments(function.arguments)`.
+//!
+//! Why: kept separate from `dto::provider` because tool calls are a property
+//! of a chat *message*, not of the request/response envelope.
+
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
 
+/// A single tool-call request emitted by the model in an assistant message.
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct ToolCall {
     pub id: String,
@@ -9,12 +20,23 @@ pub struct ToolCall {
     pub function: ToolFunction,
 }
 
+/// The function name and raw arguments payload for a `ToolCall`.
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct ToolFunction {
     pub name: String,
     pub arguments: Value,
 }
 
+/// Normalize tool-call arguments into a JSON object/value.
+///
+/// Flow: some providers send `arguments` as a JSON-encoded string rather
+/// than a nested object; if `args` is a string, attempt to parse it as
+/// JSON. Objects and other value types pass through unchanged.
+///
+/// Why: falling back to the raw string on parse failure (rather than
+/// erroring) keeps the harness resilient to malformed provider output.
+///
+/// Return: the parsed `Value`, or the original `args` clone if parsing fails.
 pub fn sanitize_tool_arguments(args: &Value) -> Value {
     match args {
         Value::String(s) => {