channels: port voice, HTTP, and Telegram onto the Channel trait

[matedev01]

Goal: move the three existing channels onto the Channel trait without behavior change.

Sub-steps

• genie-api HTTP route → trait (reference adapter).
• Voice loop → trait.
• Telegram handler → trait (preserve the telegram: sequential handle_update stalls unrelated chats #77/fix(telegram): spawn handle_update so one chat does not stall others #78 per-chat concurrency fix).

Depends on the Channel trait boundary. M2 · Workstream A.