fix: build api CLI as ESM to support trpc-cli

trpc-cli requires ESM with top-level await, which can't be loaded via
CommonJS require(). Bundle api.ts separately using esbuild as ESM (.mjs)
and use native import() via Function constructor to bypass TypeScript's
conversion to require().

Also adds `make mux` target for convenient CLI invocation.

Author: ThomasK33

Makefile

@@ -109,7 +109,7 @@ rebuild-native: node_modules/.installed ## Rebuild native modules (node-pty) for
 
 # Run compiled CLI with trailing arguments (builds only if missing)
 mux: ## Run the compiled mux CLI (e.g., make mux server --port 3000)
-	@test -f dist/cli/index.js || $(MAKE) build-main
+	@test -f dist/cli/index.js -a -f dist/cli/api.mjs || $(MAKE) build-main
 	@node dist/cli/index.js $(filter-out $@,$(MAKECMDGOALS))
 
 # Catch unknown targets passed to mux (prevents "No rule to make target" errors)
@@ -138,6 +138,7 @@ else
 dev: node_modules/.installed build-main build-preload ## Start development server (Vite + tsgo watcher for 10x faster type checking)
 	@bun x concurrently -k \
 		"bun x concurrently \"$(TSGO) -w -p tsconfig.main.json\" \"bun x tsc-alias -w -p tsconfig.main.json\"" \
+		"bun x esbuild src/cli/api.ts --bundle --format=esm --platform=node --outfile=dist/cli/api.mjs --external:zod --external:commander --external:@trpc/server --watch" \
 		"vite"
 endif
 
@@ -162,6 +163,7 @@ dev-server: node_modules/.installed build-main ## Start server mode with hot rel
 	@echo "For remote access: make dev-server VITE_HOST=0.0.0.0 BACKEND_HOST=0.0.0.0"
 	@bun x concurrently -k \
 		"bun x concurrently \"$(TSGO) -w -p tsconfig.main.json\" \"bun x tsc-alias -w -p tsconfig.main.json\"" \
+		"bun x esbuild src/cli/api.ts --bundle --format=esm --platform=node --outfile=dist/cli/api.mjs --external:zod --external:commander --external:@trpc/server --watch" \
 		"bun x nodemon --watch dist/cli/index.js --watch dist/cli/server.js --delay 500ms --exec 'NODE_ENV=development node dist/cli/index.js server --host $(or $(BACKEND_HOST),localhost) --port $(or $(BACKEND_PORT),3000)'" \
 		"MUX_VITE_HOST=$(or $(VITE_HOST),127.0.0.1) MUX_VITE_PORT=$(or $(VITE_PORT),5173) VITE_BACKEND_URL=http://$(or $(BACKEND_HOST),localhost):$(or $(BACKEND_PORT),3000) vite"
 endif

package.json

@@ -196,6 +196,7 @@
   },
   "files": [
     "dist/**/*.js",
+    "dist/**/*.mjs",
     "dist/**/*.js.map",
     "dist/**/*.wasm",
     "dist/**/*.html",

scripts/smoke-test.sh

@@ -108,6 +108,15 @@ fi
 
 log_info "✅ mux binary found"
 
+# Test that mux api subcommand works (requires ESM bundle api.mjs)
+log_info "Testing mux api subcommand (ESM bundle)..."
+if ! node_modules/.bin/mux api --help >/dev/null 2>&1; then
+  log_error "mux api --help failed - ESM bundle (api.mjs) may be missing from package"
+  exit 1
+fi
+
+log_info "✅ mux api subcommand works"
+
 # Start the server in background
 log_info "Starting mux server on $SERVER_HOST:$SERVER_PORT..."
 node_modules/.bin/mux server --host "$SERVER_HOST" --port "$SERVER_PORT" >server.log 2>&1 &