Deprecate Telegram bridge GAgents, route Telegram traffic through NyxID relay

[eanzhao]

Background

Lark traffic already flows through NyxID relay (NyxID -> Aevatar channel callback, see reference_nyxid_lark_relay). Telegram, by contrast, still has its own TelegramBridgeGAgent + TelegramUserBridgeGAgent plus the workflow YAMLs that wire it up.

If NyxID relay can carry Telegram the same way it carries Lark, these GAgents are obsolete — they become a parallel "second system" with its own state machine, contradicting CLAUDE.md "单一主干, 插件扩展".

Current Telegram-bridge surface

src/workflow/extensions/Aevatar.Workflow.Extensions.Bridge/
  TelegramBridgeGAgent.cs              (base class)
  TelegramUserBridgeGAgent.cs          (subclass)
  ServiceCollectionExtensions.cs       (DI)
test/Aevatar.Workflow.Host.Api.Tests/
  TelegramBridgeGAgentTests.cs
tools/Aevatar.Tools.Cli/workflows/
  telegram_openclaw_bridge_chat.yaml
  telegram_openclaw_file_operator.yaml
  telegram_openclaw_github_repo_research.yaml

Proposal

Phase 1 — confirm NyxID relay can carry Telegram

• Verify NyxID's /channel-relay/* endpoints support Telegram alongside Lark (NyxID #?? — check first)
• If gaps exist on the NyxID side, stop — CLAUDE.md "外部仓库无改动权" forbids requiring NyxID changes for an aevatar-side cleanup. Treat as documentation-only deprecation in that case.
• Document the relay-based Telegram callback envelope in reference_nyxid_telegram_relay (mirror of reference_nyxid_lark_relay)

Phase 2 — migrate workflows

• Convert the three telegram_openclaw_*.yaml workflows to consume NyxID relay callbacks instead of TelegramBridgeGAgent
• Maintain feature parity smoke test on Telegram bot
• Cross-reference with the channel bot relay code map (reference_channel_callback_flow)

Phase 3 — delete

• Delete TelegramBridgeGAgent, TelegramUserBridgeGAgent, related DI, tests
• CI guard against the namespace
• Update docs that reference these GAgents

Outcome

• GAgent type count: 21 → 19 (after Issue "Delete dead GAgents" lands first)
• Single unified relay path for all chat platforms (Lark + Telegram)
• One fewer parallel state machine to maintain

Risk

• Telegram-specific behavior (group/user separation, callback verification) must be preserved through the relay path
• If NyxID relay does not yet support Telegram, this issue becomes a docs-only deprecation note until that gap is closed (out of scope for this repo)