chore: bootstrap project scaffold

sidebar_window.py

@@ -0,0 +1,37 @@
+"""GTK sidebar window definitions."""
+
+from __future__ import annotations
+
+import gi
+
+gi.require_version("Gtk", "4.0")
+from gi.repository import Gtk  # noqa: E402
+
+
+class SidebarWindow(Gtk.ApplicationWindow):
+    """Minimal window placeholder to confirm the GTK application starts."""
+
+    def __init__(self, **kwargs) -> None:
+        super().__init__(**kwargs)
+        self.set_default_size(360, 640)
+        self.set_title("Niri AI Sidebar")
+
+        layout = Gtk.Box(orientation=Gtk.Orientation.VERTICAL, spacing=12)
+        layout.set_margin_top(24)
+        layout.set_margin_bottom(24)
+        layout.set_margin_start(24)
+        layout.set_margin_end(24)
+
+        title = Gtk.Label(label="AI Sidebar")
+        title.set_halign(Gtk.Align.START)
+        title.get_style_context().add_class("title-1")
+
+        message = Gtk.Label(
+            label="GTK app is running. Replace this view with the chat interface."
+        )
+        message.set_wrap(True)
+        message.set_halign(Gtk.Align.START)
+
+        layout.append(title)
+        layout.append(message)
+        self.set_child(layout)