Add The Frontier, a second setting, and a picker to choose between them

Cold Fork is a freight yard: 29 events across two stages, a four-day cycle, and
its own relationship and skill vocabulary. src/engine/ was not touched. Adding it
needed three changes outside the engine: one save slot per pack, app.js holding
the current pack, and turn.js no longer naming the mailroom (DECISIONS #34).
build.js now handles imports wrapped across lines. A conformance suite runs over
every registered pack. DECISIONS #35 records three calls on open questions.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RxdJFbLq1rBKsUeticGV1g

tools/analyze-log.js

@@ -210,19 +210,38 @@ async function main() {
     return;
   }
 
-  const runs = byRun(entries);
-  console.log(`${entries.length} turns logged across ${runs.size} run${runs.size === 1 ? '' : 's'} ` +
-    `(pack ${entries[0].pack_id} ${entries[0].pack_version ?? ''})`.trimEnd());
-  for (const [seed, run] of runs) {
-    const stages = [...new Set(run.map((e) => e.stage))];
-    console.log(`  seed ${seed}: ${run.length} turns, ${stages.join(' → ')}`);
+  // One log can hold turns from more than one setting, and pooling them would
+  // put a mailroom and a freight yard in the same repetition table. The same
+  // rule as the run boundary in DECISIONS #30, a level up: every statistic
+  // here is per pack, and a log is not one sequence.
+  const byPack = new Map();
+  for (const entry of entries) {
+    const id = entry.pack_id ?? 'unknown';
+    if (!byPack.has(id)) byPack.set(id, []);
+    byPack.get(id).push(entry);
   }
 
-  reportRepetition(runs);
-  reportChoices(entries);
-  reportGates(entries);
-  reportFeedback(entries);
-  console.log('');
+  if (byPack.size > 1) {
+    console.log(`${entries.length} turns logged across ${byPack.size} settings.`);
+  }
+
+  for (const [packId, packEntries] of byPack) {
+    const runs = byRun(packEntries);
+    console.log(
+      `${packEntries.length} turns logged across ${runs.size} run${runs.size === 1 ? '' : 's'} ` +
+      `(pack ${packId} ${packEntries[0].pack_version ?? ''})`.trimEnd(),
+    );
+    for (const [seed, run] of runs) {
+      const stages = [...new Set(run.map((e) => e.stage))];
+      console.log(`  seed ${seed}: ${run.length} turns, ${stages.join(' → ')}`);
+    }
+
+    reportRepetition(runs);
+    reportChoices(packEntries);
+    reportGates(packEntries);
+    reportFeedback(packEntries);
+    console.log('');
+  }
 }
 
 main().catch((error) => {