fix: resolve Greptile P1 close() timer leak, engine git init, dashboard test

- store.ts close(): clear retry timer and buffer before nulling _db to
  prevent re-opening a new connection after close (Greptile P1)
- merger-staging-allowlist.test.ts: use `git init -b main` so the
  default branch is always named 'main' regardless of git config
- SettingsModal.test.tsx: fix expected text for compact DroidCli card
  — shows "✓ Active" badge, not "✓ Connected — 1.2.3"

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/engine/src/__tests__/merger-staging-allowlist.test.ts

@@ -36,7 +36,7 @@ function initRepo(dir: string): string {
   const git = (cmd: string) =>
     execSync(cmd, { cwd: dir, stdio: "pipe" }).toString().trim();
 
-  git("git init");
+  git("git init -b main");
   git('git config user.email "test@example.com"');
   git('git config user.name "Test"');
   git('git config commit.gpgsign false');