chore: ignore dist.*/ build backup directories

dist.first-turn-old/ and similar hand-made build backups are not
ignored by the plain 'dist' rule, so they showed up as untracked noise
in git status.

.gitignore

@@ -8,6 +8,8 @@ pnpm-debug.log*
 lerna-debug.log*
 node_modules
 dist
+# Build backups made by hand or by deploy tooling (dist.first-turn-old/, dist.bak/ …)
+dist.*/
 playwright-report
 test-results
 dist-ssr