Initial working shell: bash-for-windows

- Cross-compiled Go-based shell for Windows (PE32+ executable)
- Builtins: cd, pwd, echo, exit, export, source, alias, type
- Coreutils: ls, cat, grep, sort, wc, head, find, cp, mv, rm, mkdir, touch, clear
- Command chaining: &&, ||, ;
- Pipes between builtins and external commands
- Variable expansion (, ) and assignment (NAME=VALUE)
- Tokenizer with single/double quote handling
- Linux and Windows (x86_64) builds via build.sh

main.go

@@ -0,0 +1,14 @@
+package main
+
+import (
+    "fmt"
+    "os"
+    "github.com/cametendo/bash-for-windows/cmd/bash"
+)
+
+func main() {
+    if err := bash.Run(); err != nil {
+        fmt.Fprintf(os.Stderr, "bash: %v\n", err)
+        os.Exit(1)
+    }
+}