Improve async validation UX in the support form

[Abidoyesimze]

Summary

Support form async validation lacks clear loading, cancellation, and field-level feedback.

Affected files

• src/components/help/SupportForm.tsx
• src/lib/form-validation.ts

Tasks

• Show per-field loading during async validation.
• Cancel in-flight validation when input changes.
• Surface clearer inline error messages.

Acceptance criteria

• Scope is limited to the files listed (or agreed alternatives in the PR).
• Change is verifiable: tests, screenshots, or written QA steps in the PR.
• No behavior regressions in related user flows.
• No new duplicate abstractions without a one-line rationale in the PR.

Suggested labels

cleanup, a11y, ux

Notes

Standalone cleanup issue from CLEANUP_ISSUES_2026-05.md. Complements the audit queue and product backlog.

[ugoocreates-pixel]

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[patience-dabo]

@patience-dabo has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hey Maintainer! This looks like an interesting issue to work on. I enjoy contributing to open-source projects and collaborating with fast-moving teams. I've reviewed the requirements and would love the opportunity to contribute. Please assign me.

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