Add native Windows support (#91)

- Native Windows daemon using TCP loopback endpoints
- Direct-mode fallback for CLI/daemon compatibility
- Comment operations over RPC
- PowerShell installer script
- Go 1.24 requirement
- Cross-OS testing documented

Co-authored-by: danshapiro <danshapiro@users.noreply.github.com>
Amp-Thread-ID: https://ampcode.com/threads/T-c6230265-055f-4af1-9712-4481061886db
Co-authored-by: Amp <amp@ampcode.com>

cmd/bd/daemon_windows.go

@@ -3,14 +3,47 @@
 package main
 
 import (
+	"os"
 	"os/exec"
 	"syscall"
+
+	"golang.org/x/sys/windows"
 )
 
+const stillActive = 259
+
+var daemonSignals = []os.Signal{os.Interrupt, syscall.SIGTERM}
+
 // configureDaemonProcess sets up platform-specific process attributes for daemon
 func configureDaemonProcess(cmd *exec.Cmd) {
-	// Windows doesn't support Setsid, use CREATE_NEW_PROCESS_GROUP instead
 	cmd.SysProcAttr = &syscall.SysProcAttr{
 		CreationFlags: syscall.CREATE_NEW_PROCESS_GROUP,
+		HideWindow:    true,
 	}
 }
+
+func sendStopSignal(process *os.Process) error {
+	if err := process.Signal(syscall.SIGTERM); err == nil {
+		return nil
+	}
+	return process.Kill()
+}
+
+func isReloadSignal(os.Signal) bool {
+	return false
+}
+
+func isProcessRunning(pid int) bool {
+	handle, err := windows.OpenProcess(windows.PROCESS_QUERY_LIMITED_INFORMATION, false, uint32(pid))
+	if err != nil {
+		return false
+	}
+	defer windows.CloseHandle(handle)
+
+	var code uint32
+	if err := windows.GetExitCodeProcess(handle, &code); err != nil {
+		return false
+	}
+
+	return code == stillActive
+}