feat: add provider-specific terminal button

Add a terminal button next to each provider card that opens a new terminal
window with that provider's specific API configuration. This allows using
different providers independently without changing the global setting.

Changes:
- Backend: Add `open_provider_terminal` command that extracts provider
  config and creates a temporary claude settings file
- Frontend: Add terminal button to provider cards with proper callback
  propagation through component hierarchy
- Support macOS (Terminal.app), Linux (gnome-terminal, konsole, etc.),
  and Windows (cmd)

Each provider gets a unique config file named `claude_<providerId>_<pid>.json`
in the temp directory, containing the provider's API configuration.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src-tauri/src/lib.rs

@@ -25,6 +25,7 @@ mod tray;
 mod usage_script;
 
 pub use app_config::{AppType, McpApps, McpServer, MultiAppConfig};
+pub use commands::open_provider_terminal;
 pub use codex_config::{get_codex_auth_path, get_codex_config_path, write_codex_live_atomic};
 pub use commands::*;
 pub use config::{get_claude_mcp_path, get_claude_settings_path, read_json_file};
@@ -689,6 +690,8 @@ pub fn run() {
             commands::get_stream_check_config,
             commands::save_stream_check_config,
             commands::get_tool_versions,
+            // Provider terminal
+            commands::open_provider_terminal,
         ]);
 
     let app = builder