feat(cli): add telegram channel adapter, scoped config, and diagnostics (replacement)

[cdenneen]

Summary

• rebased on latest upstream/dev
• squashed replacement history for Telegram adapter path
• includes scoped bridge config + diagnostics + Telegram adapter behavior

Supersedes

• feat(cli): add telegram channel adapter, scoped bridge config, and diagnostics #110

Depends on

• feat(cli): add provider-agnostic channel bridge core (replacement) #114 (core replacement)

Notes

• Replacement branch: feat/telegram-channel-adapter-v2

Summary by CodeRabbit

• New Features

  • Added a Channel Bridge for bi-directional Telegram sessions with webhook and polling modes, CLI bridge commands, daemon auto-start, and runtime config overlay.

• Bug Fixes

  • Improved KV conflict/retry resilience and safer webhook/token validation and error recovery.

• Tests

  • Broad new test coverage for adapters, worker, KV flows, overlays, CLI, and startup/shutdown edge cases.

• Documentation

  • Added Channel Bridge docs, Telegram guide, and UAT checklist; README index updated.

• UI/Diagnostics

  • Doctor enhancements: webhook validation, port parsing, secret redaction, and exit-code handling.