When a user sends a message on Telegram, the incoming message is now
automatically pinned at the start of processing and unpinned when the
agent finishes its turn. This gives the user a visual indicator that
their message is being worked on, and keeps the conversation anchored.
Changes:
- telegram.py: Added pinChatMessage in on_processing_start and
unpinChatMessage in on_processing_complete. Restructured both
hooks so pin/unpin runs independently of the reactions feature
(reactions are optional; pinning is always on).
- telegram.py: Pass message_id through SessionSource so it's
available in the session context.
- session_context.py: Added HERMES_SESSION_MESSAGE_ID context var.
- run.py: Pass source.message_id through set_session_vars.
Pinning is silent (disable_notification=True) and failures are
logged at debug level without interrupting message processing.
Only the user's incoming message is pinned -- never the agent's
replies. Auto-resume events (which have no message_id) are
correctly skipped.