Component test: EscrowCard deposit and distribute flow

[Spagero763]

Context

EscrowCard drives the deposit/distribute money path and has no test coverage, unlike the newer CreateSplit/PaySplit/RecipientEditor component tests. See app/src/components/EscrowCard.tsx.

Acceptance criteria

• A test covers the deposit button submitting an amount, and the distribute button being disabled until there's a pending balance.

Per CONTRIBUTING.md: one concern, tests required for behaviour changes. CI gate: cargo fmt / cargo clippy --all-targets -- -D warnings / cargo test for Rust, npm run build for the sdk/app.

[aliyuHabibu]

Hi, please assign this issue to me. Thank you

[Marshaltechnology]

Hello Maintainer, I'd like to work on this issue. I have experience with blockchain development and state management, and I can implement this. Please consider assigning it to me.

[grantfox-oss]

🦊 GrantFox — @Marshaltechnology has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #337)
2. Your PR will be reviewed by the tributary-protocol maintainers

Good luck! Track your progress on GrantFox.