fix: prevent permission prompts for system tools

Fixed infinite permission loop when using ExitPlanMode and other
system tools. These tools are now automatically allowed without
requiring user approval.

The issue occurred because all tool denials triggered permission
prompts, including system tools like ExitPlanMode that should never
require permission. This caused an infinite loop where:
1. Claude Code calls ExitPlanMode
2. Hikari shows permission modal
3. User approves
4. Claude Code retries ExitPlanMode
5. Loop repeats

Solution:
- Added is_system_tool helper function to identify system tools
- System tools (ExitPlanMode, EnterPlanMode) are now skipped in
  permission denial processing
- These tools execute immediately without user intervention

Closes #113

src-tauri/src/wsl_bridge.rs

@@ -1225,7 +1225,17 @@ fn process_json_line(
                         .map(|d| d.tool_use_id.clone())
                         .collect();
 
+                    // Helper function to check if a tool is a system tool that should never require permission
+                    let is_system_tool = |tool_name: &str| -> bool {
+                        matches!(tool_name, "ExitPlanMode" | "EnterPlanMode")
+                    };
+
                     for denial in denials {
+                    // Skip system tools that should never require permission
+                    if is_system_tool(&denial.tool_name) {
+                        continue;
+                    }
+
                     // Special handling for AskUserQuestion tool
                     if denial.tool_name == "AskUserQuestion" {
                         if let Some(questions) = denial