Server 2.4.0, app 2.11.1: ABRP forwarding removed from the server

The car sends live data to ABRP itself, and the car and the server go
over the same mobile connection: when the car cannot reach ABRP, it
cannot reach the server either, so the server's fallback bought
nothing. The forwarder, its ABRP_* settings and abrpSentUtc are gone;
the server only stores. The app stops sending abrpSentUtc (the server
ignores unknown fields, so 2.11.0 keeps working) and its texts no longer
promise a server fallback.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QLJfZQZeAKAwSqViTmLzki

server/model.go

@@ -107,7 +107,4 @@ type TelemetryBatch struct {
 	Samples        []TelemetrySample
 	// Dropped names the values and samples validation left out, e.g. "samples[3].speed".
 	Dropped []string
-	// AbrpSentUTC is the newest sample the car delivered to ABRP itself (0: none). The
-	// server forwards only samples newer than that, so ABRP gets each one once.
-	AbrpSentUTC int64
 }