Keep plan review cards in document flow

[LarryHu0217]

Summary

• mount the pending input, review comments, and ask-code cards in flow slots after the selected plan block
• preserve selection highlighting and sidebar scroll targeting while cleaning up slots on dismiss and unmount
• anchor multi-block selections after their final block and handle list/table markup safely
• start a fresh review session when the task, worktree, or plan content changes so stale slots and comments are not reused

Addresses the plan-review inline comment overlap item in #214.

Validation

• npm test -- src/components/plan-review-flow.test.ts (3 passed)
• npx vitest run src (65 files passed, 792 tests passed)
• npm run check
• npm run check:static
• npm run build:frontend