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_unix.go

@@ -3,11 +3,26 @@
 package main
 
 import (
+	"os"
 	"os/exec"
 	"syscall"
 )
 
+var daemonSignals = []os.Signal{syscall.SIGTERM, syscall.SIGINT, syscall.SIGHUP}
+
 // configureDaemonProcess sets up platform-specific process attributes for daemon
 func configureDaemonProcess(cmd *exec.Cmd) {
 	cmd.SysProcAttr = &syscall.SysProcAttr{Setsid: true}
 }
+
+func sendStopSignal(process *os.Process) error {
+	return process.Signal(syscall.SIGTERM)
+}
+
+func isReloadSignal(sig os.Signal) bool {
+	return sig == syscall.SIGHUP
+}
+
+func isProcessRunning(pid int) bool {
+	return syscall.Kill(pid, 0) == nil
+}