Add CI job to check that analysis_default_regression.py is always a link

.github/workflows/source.yml

@@ -30,6 +30,8 @@ jobs:
       run: .github/workflows/source/hasEOLwhiteSpace
     - name: Check test input files
       run: .github/workflows/source/check_inputs.py
+    - name: Check default analysis links
+      run: .github/workflows/source/check_analysis_file_type.py
     - name: Doxygen
       run: |
         sudo apt update

.github/workflows/source/check_analysis_file_type.py

@@ -0,0 +1,37 @@
+#! /usr/bin/env python3
+
+import sys
+from pathlib import Path
+
+# Resolve paths from this script location so the check works from any cwd.
+repo_root = Path(__file__).resolve().parents[3]
+canonical = repo_root / "Examples" / "analysis_default_regression.py"
+search_roots = [
+    repo_root / "Examples" / "Tests",
+    repo_root / "Examples" / "Physics_applications",
+]
+
+
+failed = False
+
+# Only tests and physics applications are expected to link to the shared analysis file.
+for search_root in search_roots:
+    for path in search_root.rglob("analysis_default_regression.py"):
+        path_relative = path.relative_to(repo_root)
+
+        if not path.is_symlink():
+            print(
+                f"{path_relative} must be a symlink and point to Examples/analysis_default_regression.py"
+            )
+            failed = True
+            continue
+
+        # Keep broken or unexpected links reportable instead of raising early.
+        target = path.resolve(strict=False)
+        if target != canonical:
+            print(f"{path_relative} links to {target}, expected {canonical}")
+            failed = True
+
+if failed:
+    print("FAILED")
+    sys.exit(1)