fix(presets): add border effect to border-test preset

The border-test preset had empty effects list, so no border was rendering.
Updated to include 'border' effect in the effects list, and set border=false
at the display level (since the effect handles the border rendering).

Now 'uv run mainline.py --preset border-test' correctly displays a bordered
empty frame.

presets.toml

@@ -34,12 +34,12 @@ description = "Test border rendering with empty buffer"
 source = "empty"
 display = "terminal"
 camera = "vertical"
-effects = []
+effects = ["border"]
 viewport_width = 80
 viewport_height = 24
 camera_speed = 1.0
 firehose_enabled = false
-border = true
+border = false
 
 [presets.websocket]
 description = "WebSocket display mode"