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/components/PermissionModal.svelte

@@ -87,6 +87,7 @@
           custom_instructions: config.custom_instructions || null,
           mcp_servers_json: config.mcp_servers_json || null,
           allowed_tools: newGrantedTools,
+          use_worktree: config.use_worktree ?? false,
         },
       });