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/app/workflow/script.rs

@@ -0,0 +1,37 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub enum ScriptPrimitive {
+    Agent(String),
+    Parallel(Vec<ScriptPrimitive>),
+    Pipeline(Vec<ScriptPrimitive>),
+    Phase {
+        name: String,
+        script: Box<ScriptPrimitive>,
+    },
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ScriptOptions {
+    pub max_concurrency: usize,
+    pub continue_on_error: bool,
+    pub timeout_ms: Option<u64>,
+}
+
+impl Default for ScriptOptions {
+    fn default() -> Self {
+        ScriptOptions {
+            max_concurrency: 5,
+            continue_on_error: false,
+            timeout_ms: None,
+        }
+    }
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct WorkflowScript {
+    pub name: String,
+    pub description: String,
+    pub script: ScriptPrimitive,
+    pub options: ScriptOptions,
+}