feat: add GET /routes/metrics/processors endpoint

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cameleer3-server-app/src/main/java/com/cameleer3/server/app/dto/ProcessorMetrics.java

@@ -0,0 +1,15 @@
+package com.cameleer3.server.app.dto;
+
+import jakarta.validation.constraints.NotNull;
+
+public record ProcessorMetrics(
+    @NotNull String processorId,
+    @NotNull String processorType,
+    @NotNull String routeId,
+    @NotNull String appId,
+    long totalCount,
+    long failedCount,
+    double avgDurationMs,
+    double p99DurationMs,
+    double errorRate
+) {}