0.18.1: Windows setup transport hotfix

[llblab]

Summary

This hotfix restores /telegram-setup on Windows/QEMU-style environments where native fetch can fail during bot-token validation.

It also tightens Threaded Mode terminology across release docs so Threaded Mode names the mode, thread names the Telegram UI surface, and BotFather is only described as the bot configuration tool.

Why

Issue #83 exposed that setup-time getMe validation did not use the same fallback-aware Telegram transport as normal Bot API calls. That meant a Windows/QEMU host could fail with Extension "command:telegram-setup" error: fetch failed before telegram.json was saved, even though later API paths already had IPv4 fallback support.

User-visible behavior

• /telegram-setup token validation retries native transport failures through the existing IPv4 fallback path.
• Token-check transport failures now show a clean setup notification instead of surfacing as an extension command crash.
• Docs use consistent Threaded Mode/thread language and no longer imply BotFather owns runtime Threaded Mode behavior.

Changed areas

• lib/telegram-api.ts: routes bot identity lookup through fallback-aware transport.
• lib/setup.ts: reports setup token-check transport failures as UI errors.
• tests/telegram-api.test.ts, tests/setup.test.ts: cover setup identity fallback and non-crashing setup failure behavior.
• Docs/changelog/package metadata: bumps @llblab/pi-telegram to 0.18.1 and records the Windows setup hotfix.

Risk Notes

No config migration required. The transport change is scoped to setup-time getMe validation and reuses the same fallback helper already used by JSON calls, uploads, and downloads.

Validation

• npm run validate — passed (typecheck, tests, audit, pack dry-run)
• repo_context_check /home/llb/.pi/agent/extensions/pi-telegram — passed, 0 errors / 0 warnings