fix: export RESULT_CACHE_TTL, missed by the Phase B cache-module extraction

Real regression: /api/validate references RESULT_CACHE_TTL directly
(validateCacheTTL ternary) for any ASN with >=1 announced prefix, but it
was never added to server/caches/response-caches.js's exports -- every
such request threw ReferenceError, caught by the route's own try/catch,
degrading to a 500. The smoke-test harness's fixed test ASN always hits
the empty-prefix branch locally (no real PeeringDB/DB access), so this
never got exercised by the diff-based tests -- a real blind spot.

Caught by running `eslint --rule no-undef` across server.js + server/ as
an extra verification pass (not just node --check, which only validates
syntax, not undefined-reference errors). That same pass turned up exactly
the 3 already-known pre-existing bugs from the refactor plan (fetchRPKIPerPrefix
in /api/compare, secret in /api/webhooks POST, status/roaAge in /api/health's
.catch()) and nothing else -- confirms none of the 31 already-extracted
modules have a similar issue. Will run this check at every remaining Phase C
step alongside the smoke-test diff.

Re-captured baseline (also reflects the legitimate midnight day-rollover
in the ASPA adoption tracker's daily snapshot).

server.js

@@ -97,6 +97,7 @@ const {
   responseCache,
   cacheGet,
   cacheSet,
+  RESULT_CACHE_TTL,
   CACHE_TTL_LOOKUP,
   CACHE_TTL_LOOKUP_DEGRADED,
   CACHE_TTL_DEFAULT,

server/__smoke__/baseline/baseline.json

@@ -3366,7 +3366,7 @@
     "body": {
       "__non_json__": true,
       "status": 200,
-      "bodyLength": 7058
+      "bodyLength": 7059
     }
   },
   "aspa-adoption-stats": {
@@ -3374,12 +3374,9 @@
     "body": {
       "period": "30d",
       "current": {
-        "date": "2026-07-16"
+        "date": "2026-07-17"
       },
       "trend": [
-        {
-          "date": "2026-06-16"
-        },
         {
           "date": "2026-06-17"
         },
@@ -3469,10 +3466,13 @@
         },
         {
           "date": "2026-07-16"
+        },
+        {
+          "date": "2026-07-17"
         }
       ],
       "meta": {
-        "total_snapshots": 79,
+        "total_snapshots": 80,
         "denominator": "atlas_visible_asns",
         "source": "rpki_cloudflare_feed"
       }

server/caches/response-caches.js

@@ -94,6 +94,7 @@ module.exports = {
   responseCache,
   cacheGet,
   cacheSet,
+  RESULT_CACHE_TTL,
   CACHE_TTL_LOOKUP,
   CACHE_TTL_LOOKUP_DEGRADED,
   CACHE_TTL_DEFAULT,