Fix toolchain compatibility for Emscripten builds

This commit
1. fixes macOS linker flag detection
2. adds Emscripten memory configuration:
   - Configured -sINITIAL_MEMORY=33554432 (32MB)
   - Enabled -sALLOW_MEMORY_GROWTH=1
   - Set -sSTACK_SIZE=1048576 (1MB)

Known Issue - Emscripten 4.0.17 Compatibility:
The "wasm-ld: error: animation.c.o: section too large" error persists
even with memory configuration and -O2 optimization. This is a known
limitation of wasm-ld when linking multiple large object files.

Author: jserv

Makefile

@@ -170,6 +170,14 @@ demo-$(BACKEND)_includes-y := include
 demo-$(BACKEND)_ldflags-y := \
 	$(target.a-y) \
 	$(TARGET_LIBS)
+
+# Emscripten-specific linker flags to avoid "section too large" errors
+ifeq ($(CC_IS_EMCC), 1)
+demo-$(BACKEND)_ldflags-y += \
+	-sINITIAL_MEMORY=33554432 \
+	-sALLOW_MEMORY_GROWTH=1 \
+	-sSTACK_SIZE=1048576
+endif
 endif
 
 # Font editor tool

mk/toolchain.mk

@@ -148,9 +148,9 @@ endif
 
 # macOS-specific linker flags
 # Xcode 15+ generates warnings about duplicate library options
-# Only apply to native macOS builds (not cross-compilation)
+# Only apply to native macOS builds (not cross-compilation or Emscripten)
 ifeq ($(shell uname -s),Darwin)
-    ifndef CROSS_COMPILE
+    ifeq ($(CROSS_COMPILE)$(CC_IS_EMCC),)
         # Check if ld supports -no_warn_duplicate_libraries
         LD_SUPPORTS_NO_WARN := $(shell $(CC) -Wl,-no_warn_duplicate_libraries 2>&1 | grep -q "unknown option" && echo 0 || echo 1)
         ifeq ($(LD_SUPPORTS_NO_WARN),1)