fix: increase action rate limit for drag updates in maplibre example

The live drag writeback fires at ~60Hz via requestAnimationFrame, but the
default context-level rate limit is 10 req/s (burst 20). This caused 429
responses and choppy cross-client sync during pin drags.

Raise the example app's ActionRateLimit to 60 req/s (burst 120) to
accommodate rAF-rate drag updates.

internal/examples/maplibre/main.go

@@ -82,6 +82,7 @@ func main() {
 		ServerAddress:   ":7331",
 		DevMode:         true,
 		Plugins:         []via.Plugin{maplibre.Plugin},
+		ActionRateLimit: via.RateLimitConfig{Rate: 60, Burst: 120},
 	})
 
 	// Single goroutine moves the vehicle — all clients read the same position.