fix(agui): keep interrupts resumable without expiry

[guima-why]

Summary

• remove the AG-UI adapter-specific interrupt expiry deadline
• keep pending interrupts durable across adapter and Sandbox restarts until A2A accepts a resume or cancellation
• remove the obsolete TTL CLI/config surface and update localized documentation
• update persistence, SSE, CLI, and generation-fence coverage for non-expiring interrupts

Validation

• uv run pytest -q tests/agui tests/cli/test_a2a_command.py (142 passed)
• uv run ruff check src/iac_code/agui src/iac_code/cli/main.py tests/agui tests/cli/test_a2a_command.py scripts/a2a/e2e/permission_wait/run_agui_generation_fence.py
• uv run ty check src/iac_code/agui
• git diff --check