feat: add worktree isolation support and hook event display

Closes #152, closes #150

- Add use_worktree bool to ClaudeStartOptions and HikariConfig (Rust + TS)
- Pass --worktree flag to claude in both WSL and non-WSL command paths
- Detect WorktreeCreate/WorktreeRemove hook events in stderr handler
- Emit worktree events with distinct line_type instead of error
- Add worktree line type to TerminalLine union, Terminal rendering, and tests
- Display worktree events in green with [worktree] prefix
- Add worktree isolation toggle to Agent Settings section of ConfigSidebar
- Thread use_worktree through all seven start_claude call sites

src/lib/stores/config.ts

@@ -47,6 +47,8 @@ export interface HikariConfig {
   discord_rpc_enabled: boolean;
   // Thinking blocks settings
   show_thinking_blocks: boolean;
+  // Worktree isolation
+  use_worktree: boolean;
 }
 
 const defaultConfig: HikariConfig = {
@@ -87,6 +89,7 @@ const defaultConfig: HikariConfig = {
   budget_warning_threshold: 0.8,
   discord_rpc_enabled: true,
   show_thinking_blocks: true,
+  use_worktree: false,
 };
 
 function createConfigStore() {