feat(desktop): polish community access request

[cynfria]

Why

Bring the first-community access request step in line with the approved onboarding design while preserving the existing join flow.

What

• Present public-key sharing and community URL entry as two centered steps
• Match the approved typography, translucent fields, focus treatment, and stacked footer actions
• Preserve responsive wrapping, accessibility names, validation, copy, submit, and back behavior

Risk Assessment

Low — this is a styling-only update to one onboarding view with no backend, persistence, or navigation behavior changes.

References

• just ci passed locally
• Targeted onboarding integration E2E: 3/3 passed
• Manual verification in the live worktree Tauri instance

Generated with Peppermint Butler

[wesbillman]

Safety review: the production diff is confined to WelcomeSetup.tsx; submit/validation/copy/back handlers and onboarding calls are preserved. The changes are presentation, copy, and accessibility semantics only. Current-head CI is green. I am withholding approval only because the branch is one commit behind current main; please rebase/update and let CI rerun, then this is ready for the approval gate.

[wesbillman]

Approved. The production diff remains confined to WelcomeSetup.tsx; validation, submit, clipboard, navigation, and onboarding calls are preserved. The footer submit button remains associated with the same form via form="welcome-join-form". Current head CI is green, intervening main changes do not overlap this file, and GitHub reports the PR mergeable.