feat(recording): add automatic cursor overlay

[OleksandrKucherenko]

Summary

• add opt-in video.cursorHighlight configuration for recording-wide pseudo-cursor feedback
• inject the cursor overlay when recording starts and restore it after top-level navigation
• forward cursor settings through the CLI, primary pipeline, and viewport variants
• document the configuration and cover config, runtime, CLI, recorder, and pipeline behavior with tests

Testing

• npx tsc --noEmit
• npx vitest run tests/cursor.test.ts tests/config.test.ts tests/record.test.ts tests/narration.test.ts tests/cli.test.ts
• npx vitest run tests/pipeline.test.ts -t "forwards automatic cursor highlighting"

Closes #37