Complete Phase 1: Build KiCad with optional dependencies disabled

Add CMake override modules, stub implementations, and patches to build
KiCad without CURL, libgit2, OpenCASCADE, and ngspice dependencies.

- cmake/: Find modules that provide stub targets when deps disabled
- stubs/include/: Header stubs for curl, git2, ngspice, OCC
- stubs/src/: Implementation stubs for disabled features
- patches/: Consolidated patch for KiCad source modifications
- scripts/: Build helper scripts

Verified full native build on macOS with all optional deps disabled.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

cmake/KicadWasmOptions.cmake

@@ -0,0 +1,84 @@
+#
+# KiCad WebAssembly Port - Optional Dependency Configuration
+#
+# This module defines options to disable optional dependencies for Wasm builds.
+# Include this BEFORE processing KiCad's CMakeLists.txt
+#
+
+# Optional dependency flags
+option( KICAD_USE_CURL "Enable network features (curl)" ON )
+option( KICAD_USE_GIT "Enable git integration (libgit2)" ON )
+option( KICAD_USE_OCC "Enable STEP/3D via OpenCASCADE" ON )
+option( KICAD_USE_NGSPICE "Enable SPICE simulation" ON )
+option( KICAD_USE_DATABASE "Enable database libraries (ODBC)" ON )
+
+# When building for Wasm, disable all optional deps by default
+option( KICAD_WASM_BUILD "Building for WebAssembly target" OFF )
+
+if( KICAD_WASM_BUILD )
+    message( STATUS "KiCad Wasm build: Disabling optional dependencies" )
+    set( KICAD_USE_CURL OFF CACHE BOOL "" FORCE )
+    set( KICAD_USE_GIT OFF CACHE BOOL "" FORCE )
+    set( KICAD_USE_OCC OFF CACHE BOOL "" FORCE )
+    set( KICAD_USE_NGSPICE OFF CACHE BOOL "" FORCE )
+    set( KICAD_USE_DATABASE OFF CACHE BOOL "" FORCE )
+endif()
+
+# Report status
+message( STATUS "KICAD_USE_CURL: ${KICAD_USE_CURL}" )
+message( STATUS "KICAD_USE_GIT: ${KICAD_USE_GIT}" )
+message( STATUS "KICAD_USE_OCC: ${KICAD_USE_OCC}" )
+message( STATUS "KICAD_USE_NGSPICE: ${KICAD_USE_NGSPICE}" )
+message( STATUS "KICAD_USE_DATABASE: ${KICAD_USE_DATABASE}" )
+
+#
+# Create stub/dummy targets for disabled dependencies
+#
+
+# CURL stub
+if( NOT KICAD_USE_CURL )
+    if( NOT TARGET CURL::libcurl )
+        add_library( CURL::libcurl INTERFACE IMPORTED )
+    endif()
+    add_compile_definitions( KICAD_USE_CURL=0 )
+else()
+    add_compile_definitions( KICAD_USE_CURL=1 )
+endif()
+
+# libgit2 stub
+if( NOT KICAD_USE_GIT )
+    set( LIBGIT2_FOUND TRUE )
+    set( LIBGIT2_LIBRARIES "" )
+    set( LIBGIT2_INCLUDE_DIRS "" )
+    add_compile_definitions( KICAD_USE_GIT=0 )
+else()
+    add_compile_definitions( KICAD_USE_GIT=1 )
+endif()
+
+# OpenCASCADE stub
+if( NOT KICAD_USE_OCC )
+    set( OCC_FOUND TRUE )
+    set( OCC_VERSION_STRING "7.5.0" )
+    set( OCC_INCLUDE_DIR "" )
+    set( OCC_LIBRARIES "" )
+    add_compile_definitions( KICAD_USE_OCC=0 )
+else()
+    add_compile_definitions( KICAD_USE_OCC=1 )
+endif()
+
+# ngspice stub
+if( NOT KICAD_USE_NGSPICE )
+    set( ngspice_FOUND TRUE )
+    set( NGSPICE_LIBRARY "" )
+    set( NGSPICE_INCLUDE_DIR "" )
+    add_compile_definitions( KICAD_USE_NGSPICE=0 )
+else()
+    add_compile_definitions( KICAD_USE_NGSPICE=1 )
+endif()
+
+# Database (ODBC) - affects boost::locale requirement
+if( NOT KICAD_USE_DATABASE )
+    add_compile_definitions( KICAD_USE_DATABASE=0 )
+else()
+    add_compile_definitions( KICAD_USE_DATABASE=1 )
+endif()