fix(profile): ensure extractTransactionSegment never returns numeric segments

The fallback path was returning numeric segments when all other segments
were placeholders or numeric. Now the fallback also filters out numeric
and placeholder patterns, defaulting to 'txn' if nothing meaningful found.

Fixes flaky property-based test 'does not return purely numeric segments'.

Author: BYK

src/lib/transaction-alias.ts

@@ -60,8 +60,11 @@ export function extractTransactionSegment(transaction: string): string {
     return segment.replace(/[-_]/g, "").toLowerCase();
   }
 
-  // Fallback: use first non-empty segment if no meaningful one found
-  const firstSegment = segments.find((s) => s.length > 0);
+  // Fallback: use first non-empty, non-numeric segment if no meaningful one found
+  const firstSegment = segments.find(
+    (s) =>
+      s.length > 0 && !NUMERIC_PATTERN.test(s) && !PLACEHOLDER_PATTERN.test(s)
+  );
   return firstSegment?.replace(/[-_]/g, "").toLowerCase() ?? "txn";
 }