Aggiunge monitoraggio ops: health check, log scanner, dashboard e notifiche.

Introduce incidenti con dedup, job Sidekiq ogni 3 min, scan log cron, /up/deep,
dashboard /admin/ops e push ntfy; include Sentry opzionale e fix test suite.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/config/ops_log_patterns.yml

@@ -0,0 +1,16 @@
+patterns:
+  - name: http_500
+    severity: warning
+    regex: 'Completed 500'
+  - name: disk_full
+    severity: critical
+    regex: 'No space left on device'
+  - name: db_connection
+    severity: critical
+    regex: 'PG::(ConnectionBad|UnableToSend)'
+  - name: sidekiq_failure
+    severity: warning
+    regex: 'WARN.*fail'
+  - name: fatal_error
+    severity: critical
+    regex: '\bFATAL\b'