0.18.0: thread mode

[llblab]

Summary

This release adds BotFather private-chat Thread Mode as a first-class multi-instance mode while keeping classic private DM as the base single-instance mode.

It also makes Thread Mode capability switching hot, keeps activity indication native-only through Telegram active/typing status, removes the separate telegram.json bus switch, and hardens threaded routing, lifecycle, diagnostics, transport, and validation coverage.

Why

Operators use pi-telegram in two legitimate shapes: a simple single-session bot for server/control workflows, and a multi-thread bot for development across several live Pi sessions. The release lets Telegram's own bot mode choose that shape without extra config or hidden process spawning.

User-visible behavior

• Classic private DM remains the base mode for ordinary single-instance use.
• When BotFather Thread Mode is enabled, one leader owns Telegram transport and visible follower Pi sessions join through /telegram-connect with their own thread.
• Thread Mode can hot-upgrade or return to classic mode without /reload as Telegram capability changes.
• Long-running work and compaction use only Telegram-native active/typing status; no extra progress/thinking chat surfaces are added.
• Thread-scoped replies, drafts, files, voice, buttons, menus, reactions, guest messages, and direct tools preserve their target thread.

Changed areas

• lib/polling.ts, lib/threads.ts, lib/bus-*, lib/routing.ts: Thread Mode capability, leader/follower routing, target bindings, and hot switching.
• lib/runtime.ts, lib/lifecycle.ts, lib/bindings.ts, lib/commands.ts: native typing/activity and compaction status ownership.
• lib/telegram-api.ts: Bot API transport with IPv4 fallback and redacted diagnostics.
• Docs/package metadata: release docs, backlog cleanup, and 0.18.0 changelog.

Risk Notes

• Thread Mode depends on Telegram/BotFather private-chat thread capability and client behavior; classic private DM remains the base mode when Threads are not available.
• Native Windows Thread Mode live smoke remains tracked in BACKLOG.md; named-pipe transport paths are implemented and covered where the suite can run them.
• Same-thread Telegram /new remains blocked on upstream Pi API support.

Validation

• npm run validate — passed
• git diff --check — passed