feat: add strategy and bot deletion controls

[pjy008008]

What changed

• add strategy and bot delete API client methods
• add destructive-action buttons and confirmation dialogs to the current strategy and bot UI
• refresh lists after successful deletion and surface API errors
• add API and end-to-end component coverage for both deletion flows

Why

The new backend deletion flows need a discoverable UI that matches the current application styling and prevents accidental deletion.

Behavior and impact

• deletion requires explicit confirmation
• bot deletion explains the stopped-bot restriction
• buttons, dialogs, and danger states use the existing design language
• no authentication or environment configuration was changed

Verification

• pnpm test -- --run (48 files, 579 tests)
• pnpm typecheck
• pnpm build
• git diff --check