feat(context): Ghost Drawing - suppress_commands flag

Nuevo flag para "Dibujo Fantasma":
- suppress_commands: bool en Context
- pushCommand() y pushOverlayCommand() retornan si está activo
- Permite procesar input (draw) sin generar comandos (ahorra CPU)

Solución de Gemini para immediate-mode + dirty panels

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

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

src/core/context.zig

@@ -97,6 +97,11 @@ pub const Context = struct {
     /// Dirty flags per panel (true = needs redraw)
     dirty_panels: std.StringHashMapUnmanaged(bool),
 
+    /// "Ghost Drawing" mode: when true, pushCommand does nothing.
+    /// Used to process widget input (via draw) without generating render commands.
+    /// Set by application for non-dirty panels to save CPU while keeping input working.
+    suppress_commands: bool = false,
+
     /// Frame statistics
     stats: FrameStats,
 
@@ -468,13 +473,17 @@ pub const Context = struct {
     }
 
     /// Push a draw command
+    /// If suppress_commands is true (Ghost Drawing mode), does nothing.
     pub fn pushCommand(self: *Self, cmd: Command.DrawCommand) void {
+        if (self.suppress_commands) return;
         self.commands.append(self.allocator, cmd) catch {};
     }
 
     /// Push an overlay command (drawn AFTER all regular commands)
     /// Use this for dropdowns, tooltips, popups that need to appear on top
+    /// If suppress_commands is true (Ghost Drawing mode), does nothing.
     pub fn pushOverlayCommand(self: *Self, cmd: Command.DrawCommand) void {
+        if (self.suppress_commands) return;
         self.overlay_commands.append(self.allocator, cmd) catch {};
     }