[Docs] Add stay-tuned star animation to README

[hsliuustc0106]

Why

Give readers a clear way to support system1-agents and help others discover the project.

How

Add a “Stay Tuned with Us” section before “Contributing and license” in the README, with a star request and a clickable GIF linking to this repository.

What

The GIF uses a screenshot of the actual GitHub repository page. An animated cursor demonstrates clicking Star, followed by a yellow filled star, the “Starred” label, and an incremented count. The after-click state is simulated locally for the illustration. The animation loops every 4.8 seconds and is approximately 176 KiB.

Verification

• Passed git diff --check.
• Verified the README image reference resolves and the new section appears once.
• Decoded all 31 GIF frames and verified infinite looping, 4.8-second duration, and yellow star pixels in the final frame.
• Visually reviewed the animation and the before/after button states.
• Application tests, lint, and smoke tests were not run: this change only adds README text and a GIF; no application code changes.

[Yunaik]

Thanks!