fix(ui): fix z-order - panel must be above overlay

Critical fix: The slide-in panel was appearing behind the overlay,
causing a black screen with only a weird card visible.

The problem was widget creation order:
- Before: Overlay created first, then panel
- After: Panel positioned first, then overlay, then panel lifted

Changes:
- Position panel BEFORE creating overlay
- Create overlay AFTER panel is positioned
- Call lift() AFTER both are created to ensure panel is on top

This ensures proper z-order where:
- Overlay is at the bottom (dims background)
- Panel is above overlay (visible and interactive)

Fixes: Black screen covering entire application

Related: #14
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: codewizdave

src/ui_ctk/components/slide_in_panel.py

@@ -110,7 +110,21 @@ def show(self):
         if self._visible:
             return  # Already visible
 
-        # Create overlay (dims the background)
+        # Position panel FIRST (before overlay)
+        # This ensures panel is in the widget hierarchy
+        parent_width = self.parent.winfo_width()
+        panel_width = self.cget('width')
+
+        # Position panel at right edge
+        self.place(
+            relx=1.0,  # Right edge of parent
+            x=-panel_width,  # Move left by panel width
+            y=60,  # Below navigation bar
+            relheight=1.0,
+            anchor="nw",  # Northwest anchor (top-left of panel)
+        )
+
+        # THEN create overlay (dims the background)
         self.overlay = ctk.CTkFrame(
             self.parent,
             fg_color=("gray20", "#101010"),
@@ -128,26 +142,12 @@ def show(self):
             # Escape key binding not available, that's OK
             self._esc_binding = None
 
-        # Position panel on the right side
-        # We place it at the right edge with fixed width
-        parent_width = self.parent.winfo_width()
-        panel_width = self.cget('width')
-
-        # Position panel at right edge (anchor northeast means x,y is the northeast corner)
-        self.place(
-            relx=1.0,  # Right edge of parent
-            x=-panel_width,  # Move left by panel width
-            y=60,  # Below navigation bar
-            relheight=1.0,
-            anchor="nw",  # Northwest anchor (top-left of panel)
-        )
+        # CRITICAL: Lift panel ABOVE overlay
+        self.lift()
 
         # Mark as visible
         self._visible = True
 
-        # Bring to front
-        self.lift()
-
     def close(self):
         """Close the panel and remove overlay.