fix(telegram): handle channel_post media via effective_message

[soynchux]

Summary

Fix Telegram channel_post media handling so channel photo/media posts are routed through the same effective_message path already used by text and command updates.

Previously _handle_media_message() read from update.message, which is None for Update.channel_post, causing channel media posts to be silently ignored.

Changes

• switch Telegram media handling to use effective_message
• add a regression test covering photo delivery from Update.channel_post

Test

• pytest tests/gateway/test_telegram_channel_posts.py -q

Result:

• 4 passed in 5.79s

[teknium1]

Thanks for the focused Telegram fix. I checked this against current origin/main (29c6985590043fc672a6c9a7cdb9a8695388d1ac), and the premise still holds.

Problems

• Current main still returns early in gateway/platforms/telegram.py:5995 when update.message is absent, so Telegram channel_post media can be dropped before a MessageEvent is built.
• The media handler has gained an observed-unmentioned-group branch on current main at gateway/platforms/telegram.py:5997-6007; when this is salvaged, that branch also needs to use the normalized msg, not update.message.

Suggested changes

• Apply the same _effective_update_message(update) normalization throughout _handle_media_message(): the early guard, _should_process_message, the observe branch, and the final media-processing path.
• Keep the added regression test from tests/gateway/test_telegram_channel_posts.py; it covers the right behavior for channel-post photo delivery.

Automated hermes-sweeper review; humans decide final salvage/merge.

[teknium1]

When this is salvaged onto current main, carry this normalized msg through the current observed-unmentioned-group branch too; that branch now still reads update.message, which is also None for channel_post updates.

[teknium1]

Thanks for the focused Telegram regression fix. The underlying issue still exists on current main, but the adapter was subsequently moved and gained additional intake guards.

Problems

• plugins/platforms/telegram/adapter.py:7764 still returns when update.message is absent. This conflicts with the channel-post contract documented by _effective_update_message() at plugins/platforms/telegram/adapter.py:7493-7501.
• The current handler also reads update.message throughout authorization and unmentioned-group observation (plugins/platforms/telegram/adapter.py:7766-7783). Porting only the original diff would leave those current paths dereferencing the absent field.

Suggested changes

• Resolve the effective message once at the beginning of _handle_media_message() and consistently use it throughout every guard and media path.
• Recreate the added channel-photo regression against the current plugin import in tests/gateway/test_telegram_channel_posts.py.

Automated hermes-sweeper review; humans decide final salvage/merge.