Use CLI flags instead of environment variables for master config

Replace env var parsing with Go's flag package:
- --watch (default: ../express)
- --workers (default: 1)
- --base-port (default: 3000)
- --port (default: 8080)

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

master/main.go

@@ -1,30 +1,20 @@
 package main
 
 import (
+	"flag"
 	"fmt"
 	"os"
 	"os/signal"
-	"strconv"
 	"syscall"
 )
 
 func main() {
-	watchedDir := os.Getenv("WATCHED_DIR")
+	watchDir := flag.String("watch", "../express", "directory to watch for changes")
+	workers := flag.Int("workers", 1, "number of worker processes")
+	basePort := flag.Int("base-port", 3000, "base port for worker processes")
+	listenPort := flag.Int("port", 8080, "port for the reverse proxy to listen on")
 
-	numChildProcesses := 1
-	if n, err := strconv.Atoi(os.Getenv("NUM_CHILD_PROCESSES")); err == nil && n > 0 {
-		numChildProcesses = n
-	}
-
-	basePort := 3000
-	if p, err := strconv.Atoi(os.Getenv("BASE_PORT")); err == nil && p > 0 {
-		basePort = p
-	}
-
-	listenPort := 8080
-	if p, err := strconv.Atoi(os.Getenv("LISTEN_PORT")); err == nil && p > 0 {
-		listenPort = p
-	}
+	flag.Parse()
 
 	// Create worker pool
 	pool := NewWorkerPool()
@@ -35,12 +25,12 @@ func main() {
 
 	fileChanges := make(chan FileChange, 10)
 
-	go watchFiles(watchedDir, fileChanges)
+	go watchFiles(*watchDir, fileChanges)
 
-	go runExpress(fileChanges, numChildProcesses, basePort, pool)
+	go runExpress(fileChanges, *workers, *basePort, pool)
 
 	// Start the reverse proxy
-	listenAddr := fmt.Sprintf(":%d", listenPort)
+	listenAddr := fmt.Sprintf(":%d", *listenPort)
 	go startProxy(listenAddr, pool)
 
 	// Wait for interrupt signal