Add metadata-only PPI save automation

tests/cmake/pano_cli_save_project_roundtrip.cmake

@@ -0,0 +1,59 @@
+if(NOT DEFINED PANO_CLI)
+    message(FATAL_ERROR "PANO_CLI must be set")
+endif()
+
+if(NOT DEFINED OUTPUT_PATH)
+    message(FATAL_ERROR "OUTPUT_PATH must be set")
+endif()
+
+get_filename_component(output_dir "${OUTPUT_PATH}" DIRECTORY)
+file(MAKE_DIRECTORY "${output_dir}")
+file(REMOVE "${OUTPUT_PATH}")
+
+execute_process(
+    COMMAND "${PANO_CLI}" save-project
+        --path "${OUTPUT_PATH}"
+        --width 96
+        --height 48
+        --layer-name Roundtrip
+        --frame-duration-ms 321
+    RESULT_VARIABLE save_result
+    OUTPUT_VARIABLE save_output
+    ERROR_VARIABLE save_error)
+
+if(NOT save_result EQUAL 0)
+    message(FATAL_ERROR "save-project failed: ${save_output}${save_error}")
+endif()
+
+string(FIND "${save_output}" "\"command\":\"save-project\"" save_command_index)
+string(FIND "${save_output}" "\"bytes\":65655" save_bytes_index)
+if(save_command_index LESS 0 OR save_bytes_index LESS 0)
+    message(FATAL_ERROR "save-project output did not contain expected summary: ${save_output}")
+endif()
+
+if(NOT EXISTS "${OUTPUT_PATH}")
+    message(FATAL_ERROR "save-project did not create ${OUTPUT_PATH}")
+endif()
+
+execute_process(
+    COMMAND "${PANO_CLI}" load-project --path "${OUTPUT_PATH}"
+    RESULT_VARIABLE load_result
+    OUTPUT_VARIABLE load_output
+    ERROR_VARIABLE load_error)
+
+if(NOT load_result EQUAL 0)
+    message(FATAL_ERROR "load-project failed after save-project: ${load_output}${load_error}")
+endif()
+
+string(FIND "${load_output}" "\"command\":\"load-project\"" load_command_index)
+string(FIND "${load_output}" "\"width\":96" load_width_index)
+string(FIND "${load_output}" "\"height\":48" load_height_index)
+string(FIND "${load_output}" "\"animationDurationMs\":321" load_duration_index)
+string(FIND "${load_output}" "\"layerNames\":[\"Roundtrip\"]" load_layer_index)
+if(load_command_index LESS 0
+    OR load_width_index LESS 0
+    OR load_height_index LESS 0
+    OR load_duration_index LESS 0
+    OR load_layer_index LESS 0)
+    message(FATAL_ERROR "load-project output did not contain expected round-trip summary: ${load_output}")
+endif()