fix: add missing hasAliasHitForLabel to backfill script context

Each github-script step runs in its own isolated JS context. The backfill
step was calling hasAliasHitForLabel (used by the AI alias-evidence gate)
but the function was only defined in the triage step, causing a ReferenceError
on any issue that triggered AI fallback.

Author: dgibbs64

.github/workflows/labeler.yml

@@ -1000,6 +1000,20 @@ jobs:
               return {};
             }
 
+            function hasAliasHitForLabel(text, targetLabel, gameAliasToLabel) {
+              const normalizedText = normalizeName(text);
+              if (!normalizedText || !targetLabel) return false;
+
+              const paddedText = ` ${normalizedText} `;
+              for (const [alias, label] of gameAliasToLabel.entries()) {
+                if (label !== targetLabel) continue;
+                if (alias.length < 3) continue;
+                if (paddedText.includes(` ${alias} `)) return true;
+              }
+
+              return false;
+            }
+
             function parseServerlistCsv(csvText) {
               const rows = [];
               const lines = (csvText || '').split(/\r?\n/);