docs: sync terminal demo with gbat 1.0.0

[softmaxe]

The README terminal demo showed gbat 1.0.9 while the source, release, and Homebrew package are 1.0.0. Replace it with a recording of the current build reading a connected mouse, and update both README captions.

Add a reproducible recorder that exports VHS frames and encodes them with FFmpeg to avoid the VHS 0.12.0 rendering failure. Remove the fixed battery sample wrapper and document the capture version and refresh process. Preserve the original Raycast animation byte-for-byte and document that it stays unchanged during future gbat version updates.

Validation:

• cargo check --locked --all-targets --target aarch64-apple-darwin
• cargo test --locked --target aarch64-apple-darwin: 23 tests passed
• Recorder executed successfully from outside the repository; terminal capture shows gbat 1.0.0 and real Battery: 88% output
• Shell and VHS syntax checks, full GIF decoding, README link checks, and original Raycast asset hash verification passed