Add UAC elevation support with manifest

- Added guruconnect.manifest requesting highestAvailable privileges
- Using winres to embed manifest in executable
- Added is_elevated() function to detect admin status
- Logs elevation status on startup
- Manifest includes Windows 7-11 compatibility

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

agent/build.rs

@@ -7,5 +7,26 @@ fn main() -> Result<()> {
     // Rerun if proto changes
     println!("cargo:rerun-if-changed=../proto/guruconnect.proto");
 
+    // On Windows, embed the manifest for UAC elevation
+    #[cfg(target_os = "windows")]
+    {
+        println!("cargo:rerun-if-changed=guruconnect.manifest");
+
+        let mut res = winres::WindowsResource::new();
+        res.set_manifest_file("guruconnect.manifest");
+        res.set("ProductName", "GuruConnect Agent");
+        res.set("FileDescription", "GuruConnect Remote Desktop Agent");
+        res.set("LegalCopyright", "Copyright (c) AZ Computer Guru");
+        res.set_icon("guruconnect.ico"); // Optional: add icon if available
+
+        // Only compile if the manifest exists
+        if std::path::Path::new("guruconnect.manifest").exists() {
+            if let Err(e) = res.compile() {
+                // Don't fail the build if resource compilation fails
+                eprintln!("Warning: Failed to compile Windows resources: {}", e);
+            }
+        }
+    }
+
     Ok(())
 }