fix(gui): disable window transparency for consistent Windows behavior (#428)

On Windows, when decorations are disabled for custom titlebar support,
setting transparent=true can cause issues with window hit-testing
in production builds, making custom window control buttons (minimize,
maximize, close) unresponsive or invisible.

This change:
- Sets transparent=false for all window types to match tauri.conf.json
- Removes unused vibrancy/glassmorphism code from window creation
- Ensures consistent window behavior between dev and production builds
- Fixes titlebar buttons not working on Windows in production builds

Co-authored-by: Droid Agent <droid@factory.ai>

Author: echobt

cortex-gui/src-tauri/src/window.rs

@@ -252,7 +252,7 @@ fn create_window_internal(
     let mut builder = WebviewWindowBuilder::new(app, label, WebviewUrl::App(url.into()))
         .title("Cortex")
         .decorations(false)
-        .transparent(true) // Enable for vibrancy/glassmorphism
+        .transparent(false) // Disabled - matches tauri.conf.json for consistent Windows behavior
         .visible(false); // Hidden until frontend signals UI shell is ready
 
     let is_max = if let Some(b) = bounds {
@@ -312,14 +312,11 @@ pub async fn create_new_window(app: AppHandle, path: Option<String>) -> Result<(
         .title("Cortex")
         .inner_size(1200.0, 800.0)
         .decorations(false) // Custom title bar is used
-        .transparent(true) // Enable for vibrancy/glassmorphism
+        .transparent(false) // Disabled - matches tauri.conf.json for consistent Windows behavior
         .visible(false) // Hidden until frontend signals UI shell is ready
         .build()
         .map_err(|e| format!("Failed to create window: {}", e))?;
 
-    // Apply vibrancy effect for glassmorphism
-    apply_window_vibrancy(&window);
-
     // Fallback: show window after 3 seconds if frontend hasn't signaled ready
     // This prevents invisible windows if frontend fails to load
     let window_clone = window.clone();
@@ -371,14 +368,14 @@ pub async fn create_auxiliary_window(
     let window = WebviewWindowBuilder::new(&app, label, WebviewUrl::App(url.into()))
         .title(title)
         .inner_size(width, height)
-        .decorations(true)
-        .transparent(true) // Enable for vibrancy/glassmorphism
+        .decorations(true) // Auxiliary windows use native decorations
+        .transparent(false) // Consistent with main windows
         .visible(false) // Hidden until frontend signals UI shell is ready
         .build()
         .map_err(|e| format!("Failed to create auxiliary window: {}", e))?;
 
-    // Apply vibrancy effect for glassmorphism
-    apply_window_vibrancy(&window);
+    // Show the auxiliary window (has decorations, no need to wait for custom titlebar)
+    let _ = window.show();
 
     Ok(())
 }