ci: add lightweight validation fast path

.gitea/workflows/managed-validation.yml

@@ -55,6 +55,33 @@ jobs:
             exit 1
           fi
 
+          # MANAGED_FAST_PATH: documentation and this baseline workflow cannot
+          # affect the shipped runtime. Keep the required status check, but do
+          # not install toolchains or execute the full product suite.
+          if [[ -n "${GITHUB_BASE_REF:-}" ]]; then
+            git fetch --no-tags --depth=1 origin "${GITHUB_BASE_REF}"
+            managed_base="origin/${GITHUB_BASE_REF}"
+            git diff --check "${managed_base}..HEAD"
+            mapfile -t managed_changed_files < <(
+              git diff --name-only --diff-filter=ACMR "${managed_base}..HEAD"
+            )
+            managed_runtime_change=0
+            for managed_path in "${managed_changed_files[@]}"; do
+              case "${managed_path}" in
+                *.md|*.mdx|docs/*|.github/ISSUE_TEMPLATE/*|.gitea/ISSUE_TEMPLATE/*|.gitea/runner-scope.sh|.gitea/workflows/managed-validation.yml)
+                  ;;
+                *)
+                  managed_runtime_change=1
+                  break
+                  ;;
+              esac
+            done
+            if [[ "${#managed_changed_files[@]}" -gt 0 && "${managed_runtime_change}" -eq 0 ]]; then
+              printf 'Managed validation fast path: %s non-runtime file(s); full product suite skipped.\n' \
+                "${#managed_changed_files[@]}"
+              exit 0
+            fi
+          fi
           if [[ -f pyproject.toml || -f requirements.txt ]]; then
             # Compile only tracked Python sources. Running compileall after a
             # Node install would otherwise traverse node_modules and turn a