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/settings.rs

@@ -31,8 +31,8 @@ pub struct Settings {
     pub provider: String,
     pub model: String,
     pub api_keys: std::collections::HashMap<String, String>,
-    pub max_tokens: u32,
-    pub temperature: f32,
+    pub max_tokens: Option<u32>,
+    pub temperature: Option<f32>,
     pub review_enabled: bool,
     pub review_max_lessons_per_run: usize,
     pub adaptive_review_max_skip: u32,
@@ -49,8 +49,8 @@ impl Default for Settings {
             provider: "zen".to_string(),
             model: "deepseek-v4-flash-free".to_string(),
             api_keys: std::collections::HashMap::new(),
-            max_tokens: 8192,
-            temperature: 0.7,
+            max_tokens: None,
+            temperature: None,
             review_enabled: true,
             review_max_lessons_per_run: 5,
             adaptive_review_max_skip: 3,