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/view/status.rs

@@ -50,9 +50,38 @@ pub fn draw_status_bar(frame: &mut Frame, area: Rect, state: &crate::app::state:
         status,
     ];
 
-    // Right chunk: provider · model
+    // Right chunk: token usage, provider, model
+    let right_str = if let Some(ref rt) = state.session_runtime {
+        let max_tokens = state.app_config.model_roles.values()
+            .find(|role| role.provider == state.settings.provider && role.model == state.settings.model)
+            .and_then(|role| role.context_window);
+            
+        let total_chars: usize = rt.messages.iter()
+            .filter_map(|m| m.content.as_deref())
+            .map(|c| c.len())
+            .sum();
+        let current_tokens = total_chars / 4;
+        
+        let mut parts = Vec::new();
+        if rt.usage.last_tokens_in > 0 || rt.usage.last_tokens_out > 0 {
+            parts.push(format!("↑{} ↓{}", rt.usage.last_tokens_in, rt.usage.last_tokens_out));
+        }
+        let max_str = max_tokens.map(|v| v.to_string()).unwrap_or_else(|| "?".to_string());
+        parts.push(format!("{}/{}", current_tokens, max_str));
+        parts.push(state.settings.provider.clone());
+        parts.push(state.settings.model.clone());
+        
+        format!(" {} ", parts.join(" · "))
+    } else {
+        let max_tokens = state.app_config.model_roles.values()
+            .find(|role| role.provider == state.settings.provider && role.model == state.settings.model)
+            .and_then(|role| role.context_window);
+        let max_str = max_tokens.map(|v| v.to_string()).unwrap_or_else(|| "?".to_string());
+        format!(" 0/{} · {} · {} ", max_str, state.settings.provider, state.settings.model)
+    };
+
     spans.push(Span::styled(
-        format!(" {} · {} ", state.settings.provider, state.settings.model),
+        right_str,
         Style::default().fg(Theme::DIM),
     ));