v0.2.0

feat(podkop-sub): fetch from panels that gate on a device id

Remnawave answers with a single "App not supported" placeholder unless an
x-hwid header is present. The id is derived from the MAC once and kept in the
config: the panel counts distinct ids against the account's device limit. The
User-Agent stays ours - the panel picks the response format by it, and passing
for Happ gets us an xray JSON config instead of a server list.

Two filters guard what reaches podkop. Links on 0.0.0.0 are what a panel sends
when it turns the device down, and podkop would take them for working servers.
Transports other than tcp, ws and grpc it cannot build at all: it logs
"Unknown transport" and still emits the outbound, minus the transport. Both
cases keep exit 4, now with a message that says which one happened.

An unchanged list no longer touches anything: podkop leaves config.json alone
when the generated config comes out the same, and the mtime watch read that as
a rejection - a nightly false failure with a pointless restart behind it.