feat: add browser-only WASM build to eliminate Node.js require() warnings in bundlers

When bundling sql.js for browser environments, tools like Vite, Webpack,
and esbuild emit warnings about `require("node:fs")` and
`require("node:crypto")` being externalized for browser compatibility.

This adds a new `sql-wasm-browser.js` build variant compiled with
`-s ENVIRONMENT=web,worker`, which completely eliminates Node.js code
paths from the generated JavaScript. The browser variant is exposed via
the `exports` field in package.json using the `browser` condition, so
bundlers automatically select the clean version.

The original `sql-wasm.js` with full Node.js support is preserved as
the `default` export, ensuring no breaking changes for existing users.

Closes #620

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: rxliuli

Makefile

@@ -50,6 +50,11 @@ EMFLAGS_WASM = \
 	-s WASM=1 \
 	-s ALLOW_MEMORY_GROWTH=1
 
+EMFLAGS_WASM_BROWSER = \
+	-s WASM=1 \
+	-s ALLOW_MEMORY_GROWTH=1 \
+	-s ENVIRONMENT=web,worker
+
 EMFLAGS_OPTIMIZED= \
 	-Oz \
 	-flto \
@@ -73,7 +78,7 @@ EXPORTED_METHODS_JSON_FILES = src/exported_functions.json src/exported_runtime_m
 all: optimized debug worker
 
 .PHONY: debug
-debug: dist/sql-asm-debug.js dist/sql-wasm-debug.js
+debug: dist/sql-asm-debug.js dist/sql-wasm-debug.js dist/sql-wasm-browser-debug.js
 
 dist/sql-asm-debug.js: $(BITCODE_FILES) $(OUTPUT_WRAPPER_FILES) $(SOURCE_API_FILES) $(EXPORTED_METHODS_JSON_FILES)
 	$(EMCC) $(EMFLAGS) $(EMFLAGS_DEBUG) $(EMFLAGS_ASM) $(BITCODE_FILES) $(EMFLAGS_PRE_JS_FILES) -o $@
@@ -87,8 +92,14 @@ dist/sql-wasm-debug.js: $(BITCODE_FILES) $(OUTPUT_WRAPPER_FILES) $(SOURCE_API_FI
 	cat src/shell-pre.js out/tmp-raw.js src/shell-post.js > $@
 	rm out/tmp-raw.js
 
+dist/sql-wasm-browser-debug.js: $(BITCODE_FILES) $(OUTPUT_WRAPPER_FILES) $(SOURCE_API_FILES) $(EXPORTED_METHODS_JSON_FILES)
+	$(EMCC) $(EMFLAGS) $(EMFLAGS_DEBUG) $(EMFLAGS_WASM_BROWSER) $(BITCODE_FILES) $(EMFLAGS_PRE_JS_FILES) -o $@
+	mv $@ out/tmp-raw.js
+	cat src/shell-pre.js out/tmp-raw.js src/shell-post.js > $@
+	rm out/tmp-raw.js
+
 .PHONY: optimized
-optimized: dist/sql-asm.js dist/sql-wasm.js dist/sql-asm-memory-growth.js
+optimized: dist/sql-asm.js dist/sql-wasm.js dist/sql-wasm-browser.js dist/sql-asm-memory-growth.js
 
 dist/sql-asm.js: $(BITCODE_FILES) $(OUTPUT_WRAPPER_FILES) $(SOURCE_API_FILES) $(EXPORTED_METHODS_JSON_FILES)
 	$(EMCC) $(EMFLAGS) $(EMFLAGS_OPTIMIZED) $(EMFLAGS_ASM) $(BITCODE_FILES) $(EMFLAGS_PRE_JS_FILES) -o $@
@@ -102,6 +113,12 @@ dist/sql-wasm.js: $(BITCODE_FILES) $(OUTPUT_WRAPPER_FILES) $(SOURCE_API_FILES) $
 	cat src/shell-pre.js out/tmp-raw.js src/shell-post.js > $@
 	rm out/tmp-raw.js
 
+dist/sql-wasm-browser.js: $(BITCODE_FILES) $(OUTPUT_WRAPPER_FILES) $(SOURCE_API_FILES) $(EXPORTED_METHODS_JSON_FILES)
+	$(EMCC) $(EMFLAGS) $(EMFLAGS_OPTIMIZED) $(EMFLAGS_WASM_BROWSER) $(BITCODE_FILES) $(EMFLAGS_PRE_JS_FILES) -o $@
+	mv $@ out/tmp-raw.js
+	cat src/shell-pre.js out/tmp-raw.js src/shell-post.js > $@
+	rm out/tmp-raw.js
+
 dist/sql-asm-memory-growth.js: $(BITCODE_FILES) $(OUTPUT_WRAPPER_FILES) $(SOURCE_API_FILES) $(EXPORTED_METHODS_JSON_FILES)
 	$(EMCC) $(EMFLAGS) $(EMFLAGS_OPTIMIZED) $(EMFLAGS_ASM_MEMORY_GROWTH) $(BITCODE_FILES) $(EMFLAGS_PRE_JS_FILES) -o $@
 	mv $@ out/tmp-raw.js

package.json

@@ -18,6 +18,13 @@
 	],
 	"license": "MIT",
 	"main": "./dist/sql-wasm.js",
+	"exports": {
+		".": {
+			"browser": "./dist/sql-wasm-browser.js",
+			"default": "./dist/sql-wasm.js"
+		},
+		"./dist/*": "./dist/*"
+	},
 	"scripts": {
 		"build": "make",
 		"rebuild": "npm run clean && npm run build",