chore: stop tracking config/versions.yaml (per-install Grav state)

versions.yaml records each install's Grav schema-migration state and
differs per environment (dev 2.0.4, prod 2.0.7). Tracking it in the
shared content repo caused cross-env drift; with git-sync enabled it
would push one env's version stamp to all others. Gitignore + untrack so
each install owns its own (Grav regenerates it). Mirrors the existing
treatment of security.yaml / api-private.php.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Np4cMQLF77i664CAQXySzU

.gitignore

@@ -3,9 +3,11 @@
 !/plugins/cache-on-save/
 !/plugins/story-blocks/
 /data/
+/accounts/testrunner.yaml
 /pages/01.trips/italy-2026-demo/
 /pages/02.post/*ui-test*/
 /config/plugins/git-sync.yaml
 /config/plugins/api-private.php
 /config/security.yaml
+/config/versions.yaml
 /themes/intotheeast/node_modules/