Bring the headless rig into the repository

A rendering claim about iris was verified by hand from another checkout,
because the compositor script and the input replay lived in ai-app's
submodule and not here.

`scripts/run-headless.sh` starts a headless sway on its own socket, runs
an example against it and screenshots the result. `rig-input`'s
`replay-touch` drives a recorded gesture in through Wayland's virtual
pointer, since a headless compositor has no input device to move.

`iris::harness` gains the `.touch` parser, so a recording means the same
thing replayed into a harness as into a window rather than being read
twice by two parsers.

The ai-app copy's `--phone` became `--mode`, since which phone is not
iris's business; its `IRIS_SCALE` has nothing to hand a density to here,
so it waits for one.

tests/pointer.rs

@@ -2,7 +2,7 @@
 
 use std::{cell::RefCell, rc::Rc};
 
-use iris::harness::Harness;
+use iris::harness::{Harness, TouchScript};
 use iris::prelude::*;
 
 #[test]
@@ -58,3 +58,28 @@ fn hover_ends_when_the_cursor_leaves_the_window() {
     h.leave();
     assert_eq!((*hovered.borrow(), *ended.borrow()), (1, 1));
 }
+
+#[test]
+fn a_recorded_gesture_presses_where_it_says() {
+    let mut h = Harness::new((400, 200));
+    let clicks = Rc::new(RefCell::new(Vec::new()));
+
+    let (on_left, on_right) = (clicks.clone(), clicks.clone());
+    let left = rect(Color::RED)
+        .width(100)
+        .on(CursorSense::click(), move |_, _| {
+            on_left.borrow_mut().push("left")
+        })
+        .add(&mut h.rsc);
+    let right = rect(Color::BLUE)
+        .on(CursorSense::click(), move |_, _| {
+            on_right.borrow_mut().push("right")
+        })
+        .add(&mut h.rsc);
+    h.set_root((left, right).span(Dir::RIGHT));
+
+    let script = TouchScript::parse("0 down 300 100\n80 up 300 100").unwrap();
+    h.replay(&script);
+
+    assert_eq!(*clicks.borrow(), ["right"]);
+}