feat: Windows stack (daemon, installer, GUI)

Components:
- ostp-daemon: Windows Service with Named Pipe IPC
- ostp-installer: Setup wizard with admin privileges
- ostp-gui: Tauri dark theme UI (450x600)

Features:
- Background service management (OspabGuard)
- IPC commands: CONNECT/DISCONNECT/STATUS
- Firewall rules auto-configuration
- Wintun driver placeholder (download from wintun.net)
- Real-time stats display (upload/download/ping)

Note: Requires wintun.dll download for full functionality

ostp-installer/src/main.rs

@@ -0,0 +1,88 @@
+//! OSTP Windows Installer - Setup Wizard
+//!
+//! Installs:
+//! - Wintun driver
+//! - OspabGuard Windows Service  
+//! - Firewall rules
+//! - GUI shortcuts
+
+#![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]
+
+use anyhow::{Context, Result};
+use std::path::PathBuf;
+
+mod wizard;
+mod wintun;
+mod service;
+mod firewall;
+
+// Placeholder - download actual wintun.dll from https://www.wintun.net/
+// const WINTUN_DLL: &[u8] = include_bytes!("../../assets/wintun.dll");
+
+fn main() -> Result<()> {
+    // Check for admin privileges
+    if !is_elevated() {
+        anyhow::bail!("Installer must be run as Administrator");
+    }
+
+    // Initialize logging
+    tracing_subscriber::fmt()
+        .with_max_level(tracing::Level::INFO)
+        .init();
+
+    tracing::info!("OSTP Installer starting");
+
+    // Show wizard UI
+    wizard::run_wizard()?;
+
+    Ok(())
+}
+
+#[cfg(windows)]
+fn is_elevated() -> bool {
+    use winapi::um::securitybaseapi::*;
+    use winapi::um::processthreadsapi::*;
+    use winapi::um::winnt::*;
+    use std::mem;
+    use std::ptr;
+
+    unsafe {
+        let mut handle: HANDLE = ptr::null_mut();
+        if OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, &mut handle) == 0 {
+            return false;
+        }
+
+        let mut elevation: TOKEN_ELEVATION = mem::zeroed();
+        let mut size = mem::size_of::<TOKEN_ELEVATION>() as u32;
+
+        if GetTokenInformation(
+            handle,
+            TokenElevation,
+            &mut elevation as *mut _ as *mut _,
+            size,
+            &mut size,
+        ) == 0
+        {
+            return false;
+        }
+
+        elevation.TokenIsElevated != 0
+    }
+}
+
+pub fn get_install_path() -> PathBuf {
+    PathBuf::from(r"C:\Program Files\Ospab\OSTP")
+}
+
+pub fn install_wintun_dll() -> Result<()> {
+    let install_path = get_install_path();
+    std::fs::create_dir_all(&install_path)?;
+
+    // TODO: Copy wintun.dll when available
+    // let wintun_path = install_path.join("wintun.dll");
+    // std::fs::write(&wintun_path, WINTUN_DLL)
+    //     .context("Failed to write wintun.dll")?;
+
+    tracing::info!("Wintun DLL installation placeholder");
+    Ok(())
+}