fix(bgp): сохранять неизвестные показатели без вымышленных чисел

docs/ux-ui/acceptance/bgp-nullable-replay-2026-10-12.json

@@ -0,0 +1,18 @@
+{
+  "date": "2026-10-12",
+  "block": "12.5.164",
+  "nativeSourceBlocks": [
+    160,
+    162
+  ],
+  "rows": 96,
+  "unknownCounters": 146,
+  "observedZeroCounters": 104,
+  "fourByteAsnRows": 4,
+  "passed": true,
+  "bounds": [
+    "Compiled replay of captured native160/162 data; no new native mutation",
+    "Selected numeric fields now nullable; clients must handle null, no fabricated defaults",
+    "Outbound prefix count remains unknown rather than inferred from UPDATE messages"
+  ]
+}