Add prompt processing metrics (#250)

- capture prompt processing metrics
- display prompt processing metrics on UI Activity page

proxy/metrics_middleware.go

@@ -79,10 +79,12 @@ func (rec *MetricsRecorder) parseAndRecordMetrics(jsonData gjson.Result) bool {
 	outputTokens := int(jsonData.Get("usage.completion_tokens").Int())
 	inputTokens := int(jsonData.Get("usage.prompt_tokens").Int())
 	tokensPerSecond := -1.0
+	promptPerSecond := -1.0
 	durationMs := int(time.Since(rec.startTime).Milliseconds())
 
 	// use llama-server's timing data for tok/sec and duration as it is more accurate
 	if timings := jsonData.Get("timings"); timings.Exists() {
+		promptPerSecond = jsonData.Get("timings.prompt_per_second").Float()
 		tokensPerSecond = jsonData.Get("timings.predicted_per_second").Float()
 		durationMs = int(jsonData.Get("timings.prompt_ms").Float() + jsonData.Get("timings.predicted_ms").Float())
 	}
@@ -92,6 +94,7 @@ func (rec *MetricsRecorder) parseAndRecordMetrics(jsonData gjson.Result) bool {
 		Model:           rec.realModelName,
 		InputTokens:     inputTokens,
 		OutputTokens:    outputTokens,
+		PromptPerSecond: promptPerSecond,
 		TokensPerSecond: tokensPerSecond,
 		DurationMs:      durationMs,
 	})

proxy/metrics_monitor.go

@@ -15,6 +15,7 @@ type TokenMetrics struct {
 	Model           string    `json:"model"`
 	InputTokens     int       `json:"input_tokens"`
 	OutputTokens    int       `json:"output_tokens"`
+	PromptPerSecond float64   `json:"prompt_per_second"`
 	TokensPerSecond float64   `json:"tokens_per_second"`
 	DurationMs      int       `json:"duration_ms"`
 }