fix(tui): render submitted prompts optimistically

[kitlangton]

Summary

• generate the prompt message ID in the TUI and insert it into the normal pending-input store before the request
• send the same ID to the server so session.input.admitted reconciles the local placeholder in place
• roll back rejected prompts only while they remain unconfirmed
• preserve a durably admitted prompt when the admission event arrives but the HTTP response is lost

Verification

• bun typecheck in packages/tui
• bun run test test/cli/tui/data.test.tsx test/cli/tui/session-rows.test.ts in packages/tui
• 40 focused tests covering immediate insertion, authoritative admission replacement, admission-before-error, rollback-before-late-admission, and promotion
• repository-wide pre-push typecheck