add README with features, build, and usage docs

@@ -0,0 +1,73 @@1+# Haven2+3+A lightweight macOS menu bar app for finding, setting, and managing desktop4+wallpapers. Browse [Wallhaven](https://wallhaven.cc) without leaving the menu5+bar, set any image as your wallpaper with a click, and keep a local library of6+the ones you download.7+8+## Features9+10+- **Explore** — search Wallhaven with live filtering by category11+  (General / Anime / People), purity (SFW / Sketchy), resolution, and aspect12+  ratio. Infinite scroll loads more as you go.13+- **Set instantly** — click a wallpaper to set it on your active display.14+- **Local library** — wallpapers you download are saved to a folder of your15+  choice and browsable offline. Unreadable or broken image files are skipped16+  automatically so they never clutter the view.17+- **Favorites & History** — keep the ones you love and revisit anything you've18+  set recently.19+- **Launch at login** — optionally start Haven automatically.20+21+## Requirements22+23+- macOS 13 (Ventura) or later24+- Swift 5.9+ toolchain (Xcode or the Swift command-line tools)25+26+No Wallhaven API key is required — Haven uses the public search API and browses27+SFW and Sketchy content only.28+29+## Build & Run30+31+Build a signed `.app` bundle and launch it:32+33+```sh34+./bundle_app.sh35+open Haven.app36+```37+38+Or run directly during development:39+40+```sh41+swift build42+swift run43+```44+45+Haven lives in the menu bar (it has no Dock icon). Click the menu bar icon to46+open the popover.47+48+## Usage49+50+| Tab | What it does |51+| --- | --- |52+| **Explore** | Search and browse Wallhaven. Use the slider icon to filter. |53+| **Local** | Browse wallpapers saved to your local folder. |54+| **Favorites** | Wallpapers you've hearted. |55+| **History** | Recently set wallpapers. |56+| **Settings** | Launch at login, local-save toggle, and save-folder location. |57+58+By default, downloaded wallpapers are saved to `~/Pictures/Haven`. Change this59+in **Settings → Storage → Location**.60+61+## Project Layout62+63+```64+Sources/Haven/65+  API/          Wallhaven client and response models66+  Managers/     Wallpaper, local library, favorites, history, autostart, cache67+  UI/           AppState, menu bar controller, and SwiftUI views68+  main.swift    Entry point69+```70+71+## License72+73+See the repository for license details.