feat: progressive drill-down dashboard with RED metrics and SLA compliance (#94)

Three-level dashboard driven by sidebar selection:
- L1 (no selection): all-apps overview with health table, per-app charts
- L2 (app selected): route performance table, error velocity, top errors
- L3 (route selected): processor table, latency heatmap data, bottleneck KPI

Backend: 3 new endpoints (timeseries/by-app, timeseries/by-route, errors/top),
per-app SLA settings (app_settings table, V12 migration), exact SLA compliance
from executions hypertable, error velocity with acceleration detection.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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

@@ -0,0 +1,54 @@
+package com.cameleer3.server.app.dto;
+
+import com.cameleer3.server.core.admin.AppSettings;
+import io.swagger.v3.oas.annotations.media.Schema;
+import jakarta.validation.constraints.Max;
+import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotNull;
+
+import java.time.Instant;
+import java.util.ArrayList;
+import java.util.List;
+
+@Schema(description = "Per-application dashboard settings")
+public record AppSettingsRequest(
+        @NotNull @Min(1)
+        @Schema(description = "SLA duration threshold in milliseconds")
+        Integer slaThresholdMs,
+
+        @NotNull @Min(0) @Max(100)
+        @Schema(description = "Error rate % threshold for warning (yellow) health dot")
+        Double healthErrorWarn,
+
+        @NotNull @Min(0) @Max(100)
+        @Schema(description = "Error rate % threshold for critical (red) health dot")
+        Double healthErrorCrit,
+
+        @NotNull @Min(0) @Max(100)
+        @Schema(description = "SLA compliance % threshold for warning (yellow) health dot")
+        Double healthSlaWarn,
+
+        @NotNull @Min(0) @Max(100)
+        @Schema(description = "SLA compliance % threshold for critical (red) health dot")
+        Double healthSlaCrit
+) {
+
+    public AppSettings toSettings(String appId) {
+        Instant now = Instant.now();
+        return new AppSettings(appId, slaThresholdMs, healthErrorWarn, healthErrorCrit,
+                healthSlaWarn, healthSlaCrit, now, now);
+    }
+
+    public List<String> validate() {
+        List<String> errors = new ArrayList<>();
+        if (healthErrorWarn != null && healthErrorCrit != null
+                && healthErrorWarn > healthErrorCrit) {
+            errors.add("healthErrorWarn must be <= healthErrorCrit");
+        }
+        if (healthSlaWarn != null && healthSlaCrit != null
+                && healthSlaWarn < healthSlaCrit) {
+            errors.add("healthSlaWarn must be >= healthSlaCrit (higher SLA = healthier)");
+        }
+        return errors;
+    }
+}

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

@@ -15,5 +15,6 @@ public record RouteMetrics(
         @NotNull double p99DurationMs,
         @NotNull double errorRate,
         @NotNull double throughputPerSec,
-        @NotNull List<Double> sparkline
+        @NotNull List<Double> sparkline,
+        double slaCompliance
 ) {}