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.

README.md

@@ -0,0 +1,83 @@
+# ringa
+
+GPU-rendered ring light overlay for Wayland. Simulates a monitor-mounted ring light by drawing a bright glowing border around your screen during video calls.
+
+## Features
+
+- **GPU-rendered** via wgpu/WGSL fragment shader -- smooth gaussian glow, no banding
+- **Full desktop passthrough** -- clicks, scrolls, and keyboard input pass through to your desktop
+- **Cursor avoidance** -- the ring fades near your mouse so you can see and interact with UI elements
+- **Color temperature** -- pure white default, or warm/cool/custom Kelvin presets
+- **Toggle on/off** -- bind to a hotkey; running it again kills the existing instance
+- **Works on any wlroots-based Wayland compositor** (Sway, Hyprland, niri, river, etc.)
+
+## Install
+
+### From source
+
+```sh
+git clone https://github.com/swaits/ringa.git
+cd ringa
+cargo install --path .
+```
+
+### From crates.io
+
+```sh
+cargo install ringa
+```
+
+### With mise
+
+```sh
+mise use cargo:ringa
+```
+
+## Usage
+
+```sh
+# Pure white (default)
+ringa
+
+# Color temperature presets
+ringa warm       # 3200K tungsten
+ringa golden     # 2700K golden hour
+ringa studio     # 5000K neutral studio
+ringa daylight   # 5600K daylight balanced
+ringa cool       # 6500K cool daylight
+
+# Custom Kelvin (1000-40000)
+ringa 4200
+```
+
+Run it again to toggle off.
+
+### Hotkey binding
+
+Bind `ringa` to a key in your compositor config. Examples:
+
+**Sway / i3**
+```
+bindsym $mod+F12 exec ringa
+```
+
+**Hyprland**
+```
+bind = $mainMod, F12, exec, ringa
+```
+
+**niri**
+```kdl
+binds {
+    Mod+F12 { spawn "ringa"; }
+}
+```
+
+## Requirements
+
+- Wayland compositor with `wlr-layer-shell-unstable-v1` support
+- Vulkan-capable GPU
+
+## License
+
+[MIT](LICENSE)