🔧 chore(ci): extract prepare_repo.sh and clean up workflows

- Extract shared repo-checkout logic into .gitea/ci/prepare_repo.sh,
  removing ~47 lines of duplication from standards-check.yml and test.yml
- Remove unused TEST_WORKSPACE env var from test.yml

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

.gitea/ci/sync_thirdparty_skills.sh

@@ -105,6 +105,7 @@ tracked_skill_exists() {
   [ -f "codex/skills/$name/SKILL.md" ]
 }
 
+
 cd "$REPO_DIR"
 
 git config user.name "$COMMIT_AUTHOR_NAME"
@@ -163,7 +164,7 @@ while IFS=$'\x1f' read -r source_id snapshot_dir sync_mode source_list skills_su
           echo "ERROR: duplicate third-party skill name: $name" >&2
           exit 1
         fi
-        if [ -d "codex/skills/thirdparty/$name" ] && tracked_skill_exists "$name"; then
+        if tracked_skill_exists "$name"; then
           echo "ERROR: skill name conflict with tracked skill: $name" >&2
           exit 1
         fi
@@ -180,7 +181,7 @@ while IFS=$'\x1f' read -r source_id snapshot_dir sync_mode source_list skills_su
         echo "ERROR: duplicate third-party skill name: $name" >&2
         exit 1
       fi
-      if [ -d "codex/skills/thirdparty/$name" ] && tracked_skill_exists "$name"; then
+      if tracked_skill_exists "$name"; then
         echo "ERROR: skill name conflict with tracked skill: $name" >&2
         exit 1
       fi