fix(alerting/I-1): retry endpoint resets attempts to 0 instead of incrementing

AlertNotificationRepository gains resetForRetry(UUID, Instant) which sets
attempts=0, status=PENDING, next_attempt_at=now, and clears claim/response
fields. AlertNotificationController calls resetForRetry instead of
scheduleRetry so a manual retry always starts from a clean slate.

AlertNotificationControllerIT adds retryResetsAttemptsToZero to verify
attempts==0 and status==PENDING after three prior markFailed calls.

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

cameleer-server-app/src/test/java/com/cameleer/server/app/alerting/controller/AlertNotificationControllerIT.java

@@ -113,6 +113,35 @@ class AlertNotificationControllerIT extends AbstractPostgresIT {
         assertThat(resp.getStatusCode()).isEqualTo(HttpStatus.OK);
     }
 
+    @Test
+    void retryResetsAttemptsToZero() throws Exception {
+        // Verify Fix I-1: retry endpoint resets attempts to 0, not attempts+1
+        AlertInstance instance = seedInstance();
+        AlertNotification notification = seedNotification(instance.id());
+
+        // Mark as failed with attempts at max (simulate exhausted retries)
+        notificationRepo.markFailed(notification.id(), 500, "server error");
+        notificationRepo.markFailed(notification.id(), 500, "server error");
+        notificationRepo.markFailed(notification.id(), 500, "server error");
+
+        // Verify attempts > 0 before retry
+        AlertNotification before = notificationRepo.findById(notification.id()).orElseThrow();
+        assertThat(before.attempts()).isGreaterThan(0);
+
+        // Operator retries
+        ResponseEntity<String> resp = restTemplate.exchange(
+                "/api/v1/alerts/notifications/" + notification.id() + "/retry",
+                HttpMethod.POST,
+                new HttpEntity<>(securityHelper.authHeaders(operatorJwt)),
+                String.class);
+        assertThat(resp.getStatusCode()).isEqualTo(HttpStatus.OK);
+
+        // After retry: attempts must be 0 and status PENDING (not attempts+1)
+        AlertNotification after = notificationRepo.findById(notification.id()).orElseThrow();
+        assertThat(after.attempts()).as("retry must reset attempts to 0").isEqualTo(0);
+        assertThat(after.status()).isEqualTo(NotificationStatus.PENDING);
+    }
+
     @Test
     void viewerCannotRetry() throws Exception {
         AlertInstance instance = seedInstance();