#56 docs(e2e): manual kitty verification procedure + demo inter-frame pause (K4)

Summary by Sourcery

Improve Kitty rendering verification by documenting a manual real-terminal check and making the demo pause between frames.

Enhancements:

• Add a manual verification procedure for confirming Kitty rendering, sprite movement, and background restoration in a real kitty-compatible terminal.

Documentation:

• Document prerequisites, expected visuals, platform limitations, and the relationship between manual and automated Kitty verification.

Chores:

• Pause the demo after its first frame so the initial render can be inspected before the second frame is displayed.

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Summary by cubic

Adds a manual, by-eye verification procedure for kitty rendering and pauses the demo between frames so a human can observe the first frame and the sprite's move separately.

The planned automated Linux-only E2E test (shipped via a companion PR) only proves kitty accepts the escape sequence; it cannot verify pixels render correctly, and macOS and BSD have no Xvfb equivalent.

Changes

• docs/manual-kitty-verification.md is a step-by-step procedure for real kitty-compatible terminals, including the expected output table and platform notes (BSD ships only the kitten CLI).
• examples/src/bin/demo.rs now waits for Enter between the two present() calls so the first frame and the background restoration around the moved sprite are each observable — a single present() after an in-memory move proves neither.