fix: harden Codex startup and completion notices

[Pigbibi]

Summary

• detect Codex directory trust prompts as interactive UI instead of input-ready prompts
• auto-confirm startup-only directory trust prompts before forwarding the first message to a new/recovered Codex window
• emit a small completion notice when Codex sends task_complete without a final assistant message

Tests

• uv run pytest tests/telegram_codex_bot/test_transcript_parser.py::TestParseLine::test_task_complete_without_final_message_emits_completion_notice tests/telegram_codex_bot/test_transcript_parser.py::TestParseLine::test_task_complete_with_final_message_is_skipped_to_avoid_duplicate
• uv run pytest tests/telegram_codex_bot/test_transcript_parser.py tests/telegram_codex_bot/test_session_monitor.py tests/telegram_codex_bot/test_terminal_parser.py tests/telegram_codex_bot/test_agent_input_queue.py tests/telegram_codex_bot/test_existing_window_binding.py tests/telegram_codex_bot/test_bot_topic_isolation.py
• uv run ruff check src/ tests/
• uv run pyright src/telegram_codex_bot/
• uv run pytest