Ignore composing Enter in workspace setup

[Chris0Jeky]

Summary

• ignore Enter while the workspace board-name input is composing IME text
• keep ordinary Enter on the same guarded submit path
• add a focused regression for composing and ordinary Enter behavior

Verification

• red-first focused suite: failed because composing Enter called createBoard once before the guard
• final npx vitest --run --maxWorkers=2 "src/tests/components/WorkspaceSetupModal.spec.ts" --reporter=verbose: 7 passed
• npm run typecheck: passed
• production build: passed; existing ineffective toastStore dynamic-import warning remains
• scoped ESLint: passed
• git diff --check: passed

This is the bounded keyboard residual from #2229. Date-field and release-workflow residuals remain separate.

Refs #2229

[chatgpt-codex-connector]

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