fix(app): simplify question prompt

[opencode-agent]

Summary

• hide the top-right progress segments for single-question prompts while retaining them for multiple questions
• allow users to select and copy question text

Testing

• bun typecheck (packages/app)
• bun typecheck (packages/session-ui)
• bun run test:unit (packages/app) — 439 passed
• bun test src --only-failures (packages/session-ui) — 54 passed
• existing playwright test e2e/regression/session-request-docks.spec.ts --workers=1 — 2 passed
• push hook monorepo typecheck — 29 packages passed
• production first-navigation benchmark before/after — 3 scenarios passed in both runs with zero blank samples

Visual verification

Real app UI with mocked backend request data: single-question selection and multiple-question progress.