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/subagent/spawn.rs

@@ -0,0 +1,55 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct AgentDefinition {
+    pub name: String,
+    pub role: String,
+    pub system_prompt: Option<String>,
+    pub allowed_tools: Option<Vec<String>>,
+    pub max_steps: Option<usize>,
+    pub temperature: Option<f32>,
+}
+
+impl AgentDefinition {
+    pub fn new(name: String, role: String) -> Self {
+        AgentDefinition {
+            name,
+            role,
+            system_prompt: None,
+            allowed_tools: None,
+            max_steps: None,
+            temperature: None,
+        }
+    }
+
+    pub fn with_system_prompt(mut self, prompt: String) -> Self {
+        self.system_prompt = Some(prompt);
+        self
+    }
+
+    pub fn with_allowed_tools(mut self, tools: Vec<String>) -> Self {
+        self.allowed_tools = Some(tools);
+        self
+    }
+
+    pub fn with_max_steps(mut self, steps: usize) -> Self {
+        self.max_steps = Some(steps);
+        self
+    }
+
+    pub fn with_temperature(mut self, temp: f32) -> Self {
+        self.temperature = Some(temp);
+        self
+    }
+}
+
+pub fn merge_agent_defs(base: AgentDefinition, overrides: AgentDefinition) -> AgentDefinition {
+    AgentDefinition {
+        name: base.name,
+        role: base.role,
+        system_prompt: overrides.system_prompt.or(base.system_prompt),
+        allowed_tools: overrides.allowed_tools.or(base.allowed_tools),
+        max_steps: overrides.max_steps.or(base.max_steps),
+        temperature: overrides.temperature.or(base.temperature),
+    }
+}