Add mobile Cat Blink v2 capture

[systemslibrarian]

What changed

• adds the mobile Cat Blink v2 fountain-frame decoder and golden-vector tests
• integrates blink capture sessions, progress, export, and the Cat Capture UI
• wires the browser demo to emit v2 fountain-coded eye-blink frames
• adds focused browser debugging and round-trip scripts
• fixes browser lookup of fountain classes declared as global lexical bindings

Why

The shared Cat Blink v2 wire codec was already merged, but the remaining local work connected it to the mobile camera workflow and the browser transmitter so the app can capture fountain-coded eye blinks end to end.

Validation

• mobile Jest: 25/25 Cat Blink v2 and legacy decoder tests passed
• browser codec round trip: 11/11 passed, including 40% frame loss
• development round trip: full payload and 30% loss passed
• legacy Cat Mode browser proof: 8/8 passed, including fullscreen visual-frame verification

Python pytest was unavailable in the local environment; the equivalent JavaScript cross-runtime vectors passed and CI will run the Python suite.