Add README.md files for web-app-bookwyrm, web-app-postmarks, and web-app-socialhome roles

Introduce integration test to ensure all web-app-* roles contain a README.md (required for Web App Desktop visibility)

See: https://chatgpt.com/share/68b6be49-7b78-800f-a3ff-bf922b4b083f

tests/integration/test_web_app_roles_have_readme.py

@@ -0,0 +1,66 @@
+import unittest
+from pathlib import Path
+from typing import List, Optional
+
+
+def find_repo_root(start: Path) -> Optional[Path]:
+    """
+    Walk up from `start` until we find a directory containing 'roles'.
+    Returns the repo root (the directory that contains 'roles') or None.
+    """
+    for parent in [start] + list(start.parents):
+        if (parent / "roles").is_dir():
+            return parent
+    return None
+
+
+def web_app_role_dirs(root: Path) -> List[Path]:
+    """Return all role directories that match roles/web-app-*."""
+    roles_dir = root / "roles"
+    return sorted([p for p in roles_dir.glob("web-app-*") if p.is_dir()])
+
+
+class TestWebAppRolesHaveReadme(unittest.TestCase):
+    """
+    Ensures every role under roles/web-app-* contains a README.md.
+
+    Why: The README is required for the role to be shown in the Web App Desktop.
+    """
+
+    @classmethod
+    def setUpClass(cls):
+        here = Path(__file__).resolve()
+        repo_root = find_repo_root(here.parent)
+        if repo_root is None:
+            raise RuntimeError(
+                f"Could not locate the repository root from {here}. "
+                "Expected to find a 'roles/' directory in one of the parent folders."
+            )
+        cls.repo_root = repo_root
+        cls.roles = web_app_role_dirs(repo_root)
+
+    def test_roles_directory_present(self):
+        self.assertTrue(
+            (self.repo_root / "roles").is_dir(),
+            f"'roles' directory not found at: {self.repo_root}",
+        )
+
+    def test_every_web_app_role_has_readme(self):
+        missing = []
+        for role_dir in self.roles:
+            with self.subTest(role=role_dir.name):
+                readme = role_dir / "README.md"
+                if not readme.is_file():
+                    missing.append(role_dir)
+
+        if missing:
+            formatted = "\n".join(f"- {p.relative_to(self.repo_root)}" for p in missing)
+            self.fail(
+                "The following roles are missing a README.md:\n"
+                f"{formatted}\n\n"
+                "A README.md is required so the role can be displayed in the Web App Desktop."
+            )
+
+
+if __name__ == "__main__":
+    unittest.main()