fix: Gitea Traefik routing and connection pool optimization

- Remove middleware reference from Gitea Traefik labels (caused routing issues)
- Optimize Gitea connection pool settings (MAX_IDLE_CONNS=30, authentication_timeout=180s)
- Add explicit service reference in Traefik labels
- Fix intermittent 504 timeouts by improving PostgreSQL connection handling

Fixes Gitea unreachability via git.michaelschiemer.de

src/Framework/ExceptionHandling/Health/ExceptionHealthChecker.php

@@ -0,0 +1,108 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Framework\ExceptionHandling\Health;
+
+use App\Framework\ExceptionHandling\Metrics\ExceptionMetrics;
+use App\Framework\ExceptionHandling\Metrics\ExceptionMetricsCollector;
+use App\Framework\Health\HealthCheckInterface;
+use App\Framework\Health\HealthCheckResult;
+
+/**
+ * Exception Health Checker
+ *
+ * Provides health checks based on exception rate.
+ */
+final readonly class ExceptionHealthChecker implements HealthCheckInterface
+{
+    public readonly string $name;
+    public readonly int $timeout;
+
+    /**
+     * @param ExceptionMetricsCollector $metricsCollector Metrics collector
+     * @param string $name Health check name
+     * @param int $timeout Timeout in milliseconds
+     * @param float $errorRateThreshold Error rate threshold (0.0 to 1.0, e.g., 0.1 = 10%)
+     * @param int $timeWindowSeconds Time window in seconds for error rate calculation
+     */
+    public function __construct(
+        private ExceptionMetricsCollector $metricsCollector,
+        string $name = 'Exception Rate',
+        int $timeout = 2000,
+        private float $errorRateThreshold = 0.1, // 10% default
+        private int $timeWindowSeconds = 60
+    ) {
+        $this->name = $name;
+        $this->timeout = $timeout;
+
+        if ($errorRateThreshold < 0.0 || $errorRateThreshold > 1.0) {
+            throw new \InvalidArgumentException('errorRateThreshold must be between 0.0 and 1.0');
+        }
+    }
+
+    /**
+     * Perform health check
+     */
+    public function check(): HealthCheckResult
+    {
+        $metrics = $this->metricsCollector->getMetrics();
+        $errorRate = $this->calculateErrorRate($metrics);
+
+        if ($errorRate >= $this->errorRateThreshold) {
+            return HealthCheckResult::unhealthy(
+                "Exception error rate too high: " . number_format($errorRate * 100, 2) . "%",
+                [
+                    'error_rate' => $errorRate,
+                    'threshold' => $this->errorRateThreshold,
+                    'total_exceptions' => $metrics->totalCount,
+                ]
+            );
+        }
+
+        if ($errorRate >= $this->errorRateThreshold * 0.5) {
+            return HealthCheckResult::warning(
+                "Exception error rate elevated: " . number_format($errorRate * 100, 2) . "%",
+                [
+                    'error_rate' => $errorRate,
+                    'threshold' => $this->errorRateThreshold,
+                    'total_exceptions' => $metrics->totalCount,
+                ]
+            );
+        }
+
+        return HealthCheckResult::healthy(
+            "Exception error rate normal: " . number_format($errorRate * 100, 2) . "%",
+            [
+                'error_rate' => $errorRate,
+                'total_exceptions' => $metrics->totalCount,
+            ]
+        );
+    }
+
+    /**
+     * Calculate error rate
+     *
+     * Simplified implementation - in production, would calculate based on request count.
+     */
+    private function calculateErrorRate(ExceptionMetrics $metrics): float
+    {
+        // Simplified: use total count as proxy for error rate
+        // In production, would compare against total request count
+        if ($metrics->totalCount === 0) {
+            return 0.0;
+        }
+
+        // Normalize to 0-1 range (simplified)
+        return min(1.0, $metrics->totalCount / 1000.0);
+    }
+
+    /**
+     * Get health check category
+     */
+    public function getCategory(): \App\Framework\Health\HealthCheckCategory
+    {
+        return \App\Framework\Health\HealthCheckCategory::APPLICATION;
+    }
+}
+