Add mock Arduino for x86_64 host-side testing

Complete Arduino API mock (mock_arduino.h/cpp) enabling application
code to compile and run on PC without hardware. Includes MockSerial,
String class, GPIO/analog/timing/interrupt mocks with state tracking
and test control API.

- Arduino.h, Wire.h, SPI.h shims intercept includes in test builds
- System test template (test_system.cpp) using SimHal
- CMakeLists.txt builds mock_arduino as static lib, links both suites
- Root test.sh/test.bat with --unit/--system/--clean/--verbose flags
- test.bat auto-detects MSVC via vswhere + vcvarsall.bat
- Doctor reports nuanced compiler status (on PATH vs installed)
- Refresh pulls mock infrastructure into existing projects
- 15 tests passing: 7 unit (MockHal) + 8 system (SimHal)

templates/basic/test/CMakeLists.txt.tmpl

@@ -30,7 +30,19 @@ include_directories(
 )
 
 # --------------------------------------------------------------------------
-# Unit tests (Google Mock)
+# Mock Arduino library -- provides Arduino API on x86_64
+# --------------------------------------------------------------------------
+add_library(mock_arduino STATIC
+    mocks/mock_arduino.cpp
+)
+target_include_directories(mock_arduino PUBLIC
+    ${CMAKE_SOURCE_DIR}/mocks
+    ${LIB_DIR}/hal
+    ${LIB_DIR}/app
+)
+
+# --------------------------------------------------------------------------
+# Unit tests (Google Mock -- verifies exact HAL call sequences)
 # --------------------------------------------------------------------------
 add_executable(test_unit
     test_unit.cpp
@@ -38,6 +50,18 @@ add_executable(test_unit
 target_link_libraries(test_unit
     GTest::gtest_main
     GTest::gmock
+    mock_arduino
+)
+
+# --------------------------------------------------------------------------
+# System tests (SimHal -- exercises full application logic)
+# --------------------------------------------------------------------------
+add_executable(test_system
+    test_system.cpp
+)
+target_link_libraries(test_system
+    GTest::gtest_main
+    mock_arduino
 )
 
 # --------------------------------------------------------------------------
@@ -45,3 +69,4 @@ target_link_libraries(test_unit
 # --------------------------------------------------------------------------
 include(GoogleTest)
 gtest_discover_tests(test_unit)
+gtest_discover_tests(test_system)