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/model/app_config.rs

@@ -0,0 +1,60 @@
+use serde::{Deserialize, Serialize};
+use std::collections::HashMap;
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct AppConfig {
+    pub providers: HashMap<String, ProviderConfig>,
+    pub model_roles: HashMap<String, ModelRole>,
+    pub default_provider: String,
+    pub default_model: String,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ProviderConfig {
+    pub api_base: String,
+    pub api_key_env: Option<String>,
+    pub default_model: Option<String>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ModelRole {
+    pub provider: String,
+    pub model: String,
+    pub max_tokens: Option<u32>,
+    pub temperature: Option<f32>,
+}
+
+impl Default for AppConfig {
+    fn default() -> Self {
+        let mut providers = HashMap::new();
+        providers.insert("openrouter".to_string(), ProviderConfig {
+            api_base: "https://openrouter.ai/api/v1".to_string(),
+            api_key_env: Some("OPENROUTER_API_KEY".to_string()),
+            default_model: Some("anthropic/claude-opus-4-8".to_string()),
+        });
+        let mut model_roles = HashMap::new();
+        model_roles.insert("default".to_string(), ModelRole {
+            provider: "openrouter".to_string(),
+            model: "anthropic/claude-opus-4-8".to_string(),
+            max_tokens: Some(8192),
+            temperature: Some(0.7),
+        });
+        AppConfig {
+            providers,
+            model_roles,
+            default_provider: "openrouter".to_string(),
+            default_model: "anthropic/claude-opus-4-8".to_string(),
+        }
+    }
+}
+
+impl AppConfig {
+    pub fn load() -> Self {
+        let store = super::store::Store::new();
+        let path = store.base_dir.join("app_config.json");
+        std::fs::read_to_string(path)
+            .ok()
+            .and_then(|s| serde_json::from_str(&s).ok())
+            .unwrap_or_default()
+    }
+}