feat(schematic): eeschema WASM build + e2e harness

wasm/stubs/eeschema_frame_stub.cpp

@@ -0,0 +1,15 @@
+/*
+ * Eeschema frame stubs for KiCad WASM build.
+ *
+ * Mirror of pcb_frame_stub.cpp. Populate as linker errors surface during the
+ * first eeschema-wasm build. Methods that need to be stubbed are typically:
+ *   - Scripting helpers (LoadSchematic / SaveSchematic) when KICAD_SCRIPTING=OFF
+ *   - Action-plugin glue (no plugins in WASM)
+ *   - Filesystem-watcher hooks when wxUSE_FSWATCHER=0
+ *
+ * Leave this file empty until the linker complains; the build script skips
+ * compiling it when it has zero bytes.
+ */
+
+#ifdef __EMSCRIPTEN__
+#endif