Drop pacman packaging, bakery-only; fix broken Tauri build path in CI

bakery.toml gains license_file/desktop_file (closing the same gap found
across the rest of the ecosystem) plus hicolor-icon-theme as an optional
dep. Removes packaging/PKGBUILD and .forgejo/workflows/package.yml.

Also fixes release.yml, which has never actually succeeded since the
GTK4->Tauri migration (93c3b88): Cargo.toml moved to src/src/Cargo.toml
(the checkout dir is conventionally named "src", and this repo's own
Rust backend directory is *also* named "src", not the usual src-tauri),
and the Rust build needs frontend/build to already exist (tauri.conf.json's
frontendDist) — that's normally handled by `cargo tauri build`'s
beforeBuildCommand hook, which a plain `cargo build` never runs, so it's
now a separate explicit "build frontend" step. Adds dev-release.yml/
beta-release.yml for the same three-track policy used ecosystem-wide.

packaging/PKGBUILD

@@ -1,38 +0,0 @@
-# Maintainer: Breadway <plasticbread849@gmail.com>
-
-pkgname=bos-settings
-pkgver=0.1.0
-pkgrel=1
-pkgdesc="System settings app for Bread OS"
-arch=('x86_64')
-url="https://git.breadway.dev/Breadway/bos-settings"
-license=('MIT')
-# Some Rust deps (ring/mlua) build vendored C/asm into static archives; makepkg's
-# default -flto=auto emits GCC LTO bitcode the Rust (lld) link cannot read,
-# causing undefined-symbol errors. Disable LTO.
-options=(!lto !debug)
-depends=('gtk4' 'glib2' 'hicolor-icon-theme')
-optdepends=(
-  'snapper: snapshot management view'
-)
-makedepends=('rust' 'cargo')
-source=("${pkgname}-${pkgver}.tar.gz")
-sha256sums=('SKIP')
-
-build() {
-  cd "${srcdir}/${pkgname}-${pkgver}"
-  cargo build --release --locked
-}
-
-check() {
-  cd "${srcdir}/${pkgname}-${pkgver}"
-  cargo test --release --locked
-}
-
-package() {
-  cd "${srcdir}/${pkgname}-${pkgver}"
-  install -Dm755 target/release/bos-settings "${pkgdir}/usr/bin/bos-settings"
-  install -Dm644 packaging/bos-settings.desktop \
-    "${pkgdir}/usr/share/applications/bos-settings.desktop"
-  install -Dm644 LICENSE "${pkgdir}/usr/share/licenses/${pkgname}/LICENSE"
-}

packaging/README.md

@@ -1,25 +0,0 @@
-Arch packaging
-==============
-
-`PKGBUILD` builds and installs `bos-settings` from source.
-
-## Local build
-
-```bash
-makepkg -si
-```
-
-## Before publishing to [breadway] repo
-
-1. Tag a release on GitHub.
-2. Update `pkgver` to match the tag.
-3. Update `source` to the release tarball URL.
-4. Run `updpkgsums` (or manually set `sha256sums`).
-
-## Runtime dependencies
-
-| Package | Required | Notes |
-|---------|----------|-------|
-| `gtk4` | yes | UI toolkit |
-| `glib2` | yes | always |
-| `snapper` | optional | snapshot management view |