Introduces a minimal Addon interface (Start, HandleDMCommand,
HandleDMForward) wired into the bridge:
- bridge.go: Bridge gains an addon field, started as a goroutine in Run
when non-nil; loadAddon is provided per build configuration.
- addon_stub.go (default build, //go:build !addon): loadAddon returns
nil — the public binary has no addon and no extra behavior.
- telegram.go: private-chat messages and channel forwards are offered to
the addon first when present; if it handles them, the bridge skips its
own processing. No-op in the public build.
- TGSender.ForwardMessage(from, to, msgID, silent) added — a generic Bot
API wrapper returning the full message; useful for any addon that needs
to relay existing messages.
The concrete addon implementation is compiled separately via the `addon`
build tag and is not part of this repository.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
