feat(android): add percent shortcuts to swap pay input

[jonathanchw]

Adds 25% / 50% / 100% quick-fill buttons to the swap pay input field.

When the pay amount field is focused, the bottom action bar is replaced by a PayPercentBar showing percent options and a "Done" button to dismiss the keyboard.

• SwapScene — renders PayPercentBar in place of the swap button when keyboard is open and pay field is editable
• SwapViewModel — onSelectPayPercent(percent) scales the available balance and sets the pay field value
• SwapScreen — wires onSelectPayPercent to the ViewModel

video5127607918203504612.mp4

[jonathanchw]

The Android Tests / Unit Tests check failed due to the self-hosted runner losing connection mid-build (not a code issue). Please re-run the job by clicking "Re-run failed jobs" on the checks section.

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The self-hosted runner lost communication with the server. Verify the machine is running and has a healthy network connection. Anything in your workflow that terminates the runner process, starves it for CPU/Memory, or blocks its network access can cause this error.

[gemcoder21]

Closing for now, will make adjustments in separate commit with changes to the swap