feat(lsp): implement LSP client and server management

- Added LspClient for handling communication with LSP servers, including methods for initialization, notifications, and requests.
- Introduced LspManager to manage multiple LSP server connections, allowing for connection, disconnection, and retrieval of server capabilities.
- Created tools for connecting to LSP servers, retrieving diagnostics, hover information, code completion, definitions, and references.
- Enhanced UI rendering to display token usage and settings in the overlay.
- Updated status bar to show current token usage and selected provider/model.

src/model/app_config.rs

@@ -12,6 +12,7 @@ pub struct AppConfig {
     pub model_roles: HashMap<String, ModelRole>,
     pub default_provider: String,
     pub default_model: String,
+    pub default_context_window: u32,
 }
 
 /// Connection details for a single LLM provider (base URL, API key source).
@@ -30,6 +31,7 @@ pub struct ModelRole {
     pub provider: String,
     pub model: String,
     pub max_tokens: Option<u32>,
+    pub context_window: Option<u32>,
     pub temperature: Option<f32>,
 }
 
@@ -52,7 +54,8 @@ impl Default for AppConfig {
         model_roles.insert("default".to_string(), ModelRole {
             provider: "zen".to_string(),
             model: "deepseek-v4-flash-free".to_string(),
-            max_tokens: Some(8192),
+            max_tokens: None,
+            context_window: None,
             temperature: Some(0.7),
         });
         AppConfig {
@@ -60,6 +63,7 @@ impl Default for AppConfig {
             model_roles,
             default_provider: "zen".to_string(),
             default_model: "deepseek-v4-flash-free".to_string(),
+            default_context_window: 256_000,
         }
     }
 }