Implement chat and markdown views, enhance status bar, and add workflow panel

- Added `chat.rs` for rendering chat messages with timestamps and roles.
- Introduced `markdown.rs` for rendering markdown content with styling.
- Created `status.rs` to display the application status bar with session and message counts.
- Developed `workflow.rs` to show the current workflow status, including tool calls and active jobs.
- Established a `theme.rs` for centralized color management across the UI.
- Updated `mod.rs` to include new modules and manage rendering logic.

src/tool/workflow.rs

@@ -0,0 +1,41 @@
+use serde_json::{json, Value};
+use anyhow::{Result, anyhow};
+use super::Tool;
+use super::ToolCtx;
+
+pub struct WorkflowRun;
+
+impl Tool for WorkflowRun {
+    fn name(&self) -> &'static str {
+        "workflow_run"
+    }
+
+    fn description(&self) -> &'static str {
+        "Execute a workflow script by delegating to the workflow engine"
+    }
+
+    fn parameters(&self) -> Value {
+        json!({
+            "type": "object",
+            "properties": {
+                "script": {
+                    "type": "string",
+                    "description": "Workflow script content or path to a workflow file"
+                },
+                "args": {
+                    "type": "object",
+                    "description": "Optional arguments passed to the workflow script"
+                }
+            },
+            "required": ["script"]
+        })
+    }
+
+    fn run(&self, _ctx: &ToolCtx, args: &Value) -> Result<String> {
+        let _script = args.get("script")
+            .and_then(|v| v.as_str())
+            .ok_or_else(|| anyhow!("missing required argument: script"))?;
+        let _workflow_args = args.get("args");
+        Ok("workflow delegated to workflow engine".to_string())
+    }
+}