fix(telegram): rename runtime-discovered DM topics

[tianma-if]

Summary

• distinguish operator-declared Telegram DM topics from runtime-discovered topic-name cache entries before auto-rename
• allow newly created topics such as Telegram's default "New Thread" to be renamed from the generated session title
• add regression coverage that preserves the existing operator-declared topic guard

Fixes #57341

Tests

• .venv/bin/python -m pytest tests/gateway/test_telegram_topic_mode.py -q
• .venv/bin/python -m ruff check gateway/run.py tests/gateway/test_telegram_topic_mode.py

[teknium1]

Thanks for isolating the runtime-cache versus operator-config distinction; the current-head code confirms that this is a real bug.

Problems

• The PR is conflicting, and its historical self.adapters.get(source.platform) lookup must not be carried forward. Current main resolves this path with self._adapter_for_source(source) at gateway/run.py:13906; that resolver preserves secondary-profile adapter isolation in gateway/authz_mixin.py:41-70.

Suggested changes

• Salvage the new _dm_topics_config membership check after current main's source-aware adapter resolution, rather than replacing it with the PR's older lookup.
• Keep the added runtime-cache regression coverage; plugins/platforms/telegram/adapter.py:8522-8548 confirms why the prior dict-based guard incorrectly classifies cached topics as configured ones.

Automated hermes-sweeper review.