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.

Cargo.toml

@@ -20,7 +20,7 @@ tokio = { workspace = true, features = ["sync", "rt", "rt-multi-thread"] }
 tokio = { workspace = true, features = ["sync", "rt", "rt-multi-thread", "time"] }
 
 [workspace]
-members = ["core", "macro"]
+members = ["core", "macro", "rig-input"]
 
 [workspace.package]
 version = "0.1.0"
@@ -40,3 +40,5 @@ arboard = "3.6.1"
 iris-core = { path = "core" }
 iris-macro = { path = "macro" }
 tokio = "1.49.0"
+wayland-client = "0.31.15"
+wayland-protocols-wlr = { version = "0.3.12", features = ["client"] }