fix(FN-000): skip qmd index mutations in test runs

Why: tests were leaking ~700 per-temp-dir collection registrations
into the user's global ~/.config/qmd/index.yml because searchWithQmd
and the agent-memory qmd path called execFile("qmd", ...) with the
real binary, bypassing shouldSkipBackgroundQmdRefresh() which only
guarded the schedule* wrappers.

Guard both direct-execFile paths under the same skip flag and fall
back to file-based agent memory search when skipping.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/core/src/index.ts

@@ -452,6 +452,7 @@ export {
   buildQmdRefreshCommands,
   refreshQmdProjectMemoryIndex,
   scheduleQmdProjectMemoryRefresh,
+  shouldSkipBackgroundQmdRefresh,
   installQmd,
   ensureQmdInstalled,
   ensureQmdInstalledAndRefresh,

packages/core/src/memory-backend.ts

@@ -857,6 +857,9 @@ function normalizeQmdSearchResultPath(rootDir: string, rawPath: unknown): string
 }
 
 async function searchWithQmd(rootDir: string, options: MemorySearchOptions): Promise<MemorySearchResult[]> {
+  if (shouldSkipBackgroundQmdRefresh()) {
+    return [];
+  }
   const command = "qmd";
   const limit = Math.max(1, Math.min(options.limit ?? 5, 20));
   try {