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>

internal/rpc/signals_unix.go

@@ -0,0 +1,10 @@
+//go:build !windows
+
+package rpc
+
+import (
+	"os"
+	"syscall"
+)
+
+var serverSignals = []os.Signal{syscall.SIGINT, syscall.SIGTERM}