chore: add LICENSE, README, CHANGELOG, and publish metadata

Add MIT license, README with usage/install instructions and hotkey
binding examples, CHANGELOG for v0.1.0, and complete Cargo.toml
metadata (repository, homepage, keywords, categories). Remove unused
niri-ipc dependency.

Cargo.toml

@@ -2,14 +2,19 @@
 name = "ringa"
 version = "0.1.0"
 edition = "2021"
-description = "Wayland ring light overlay"
+license = "MIT"
+description = "GPU-rendered ring light overlay for Wayland"
+repository = "https://github.com/swaits/ringa"
+homepage = "https://github.com/swaits/ringa"
+readme = "README.md"
+keywords = ["wayland", "ring-light", "overlay", "wgpu", "camera"]
+categories = ["command-line-utilities", "multimedia"]
 authors = ["Stephen Waits <steve@waits.net>"]
 rust-version = "1.85"
 
 [dependencies]
 anyhow = "1.0"
 bytemuck = { version = "1", features = ["derive"] }
-niri-ipc = "25.11.0"
 nix = { version = "0.29", features = ["signal", "process", "poll"] }
 pollster = "0.4"
 raw-window-handle = "0.6"