feat(poc): rewind MCP, skill, and recover-ladder docs

Initial PoC: find_protection, tagged checkpoints, FLR, mutating catalog.
Lab 10.9 status enums (0=Initializing, 1=MeetingSLA). Credentials stay in gitignored config.json.

tests/test_catalog.py

@@ -0,0 +1,33 @@
+import json
+from pathlib import Path
+
+from zerto_rewind_mcp.catalog import CatalogEntry, MutatingCatalog, entry_from_dict
+
+
+def test_add_and_get(tmp_path: Path):
+    path = tmp_path / "config.json"
+    path.write_text(
+        json.dumps({"zerto_url": "https://zvm", "mutating_tools": []}),
+        encoding="utf-8",
+    )
+    cat = MutatingCatalog(path=path)
+    cat.add(CatalogEntry(server="ssh", tool="exec", vm_arg="host", notes="guest shell"))
+    found = cat.get("SSH", "Exec")
+    assert found is not None
+    assert found.vm_arg == "host"
+    saved = json.loads(path.read_text(encoding="utf-8"))
+    assert saved["zerto_url"] == "https://zvm"
+    assert saved["mutating_tools"][0]["tool"] == "exec"
+
+
+def test_unlisted_is_missing():
+    cat = MutatingCatalog()
+    assert cat.get("foo", "bar") is None
+
+
+def test_entry_requires_fields():
+    try:
+        entry_from_dict({"server": "ssh"})
+        raise AssertionError("expected ValueError")
+    except ValueError:
+        pass