feat(claude-binary): implement robust version selector with enhanced binary detection

This commit provides a comprehensive solution to Claude binary detection issues
by implementing a user-friendly version selector UI and improving the binary
discovery logic. It addresses all concerns raised in multiple PRs and comments.

Changes:
- Add ClaudeVersionSelector component for selecting from multiple installations
- Update ClaudeBinaryDialog to use version selector instead of manual path input
- Fix unused variable warning in production builds (claude.rs:442)
- Improve select_best_installation to handle production build restrictions
- Add listClaudeInstallations API endpoint to fetch all available installations
- Make Claude version indicator clickable to navigate to Settings
- Move Claude installation selector to General tab in Settings (per user request)
- Enhance dialog UX with loading states and clear installation instructions
- Add Radix UI radio-group dependency for version selector

Fixes:
- Production build warning about unused claude_path variable
- Version detection failures in production builds due to process restrictions
- Poor UX when Claude binary is not found (now shows helpful dialog)
- Inability to easily switch between multiple Claude installations

This implementation takes inspiration from:
- PR #3: Version selector dropdown approach (preferred by users)
- PR #4: Binary detection improvements and path validation
- PR #39: Additional detection methods and error handling
- Commit 5a29f9a: Shared claude binary detection module architecture

Addresses feedback from:
- getAsterisk/claudia#4 (comment): User preference for dropdown selector
- Production build restrictions that prevent version detection
- Need for better error handling when Claude is not installed

The solution provides a seamless experience whether Claude is installed via:
- npm/yarn/bun global installation
- nvm-managed Node.js versions
- Homebrew on macOS
- System-wide installation
- Local user installation (~/.local/bin, etc.)

Refs: #3, #4, #39, 5a29f9a

src-tauri/src/commands/agents.rs

@@ -1807,6 +1807,18 @@ pub async fn set_claude_binary_path(db: State<'_, AgentDb>, path: String) -> Res
     Ok(())
 }
 
+/// List all available Claude installations on the system
+#[tauri::command]
+pub async fn list_claude_installations() -> Result<Vec<crate::claude_binary::ClaudeInstallation>, String> {
+    let installations = crate::claude_binary::discover_claude_installations();
+    
+    if installations.is_empty() {
+        return Err("No Claude Code installations found on the system".to_string());
+    }
+    
+    Ok(installations)
+}
+
 /// Helper function to create a tokio Command with proper environment variables
 /// This ensures commands like Claude can find Node.js and other dependencies
 fn create_command_with_env(program: &str) -> Command {

src-tauri/src/commands/claude.rs

@@ -440,6 +440,10 @@ pub async fn get_claude_settings() -> Result<ClaudeSettings, String> {
 pub async fn open_new_session(app: AppHandle, path: Option<String>) -> Result<String, String> {
     log::info!("Opening new Claude Code session at path: {:?}", path);
     
+    #[cfg(not(debug_assertions))]
+    let _claude_path = find_claude_binary(&app)?;
+    
+    #[cfg(debug_assertions)]
     let claude_path = find_claude_binary(&app)?;
     
     // In production, we can't use std::process::Command directly