feat(soak): scaffold tests/soak package

Placeholder runner, tsconfig with @bot alias to tests/e2e/bot,
gitignored .env.stresstest + artifacts. Real behavior follows
in Task 10 onward.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/soak/runner.ts

@@ -0,0 +1,16 @@
+#!/usr/bin/env tsx
+/**
+ * Golf Soak Harness — entry point.
+ *
+ * Placeholder. Full runner lands in Task 18.
+ */
+
+async function main(): Promise<void> {
+  console.log('golf-soak runner (placeholder)');
+  console.log('Full implementation lands in Task 18 of the plan.');
+}
+
+main().catch((err) => {
+  console.error(err);
+  process.exit(1);
+});