M10 (task 2022, issue 2021): Arch pacman package + commit icon set (native, system libs)

Native-first fix for the AppImage black window: a PKGBUILD that builds from source,
linked against SYSTEM graphics libs, so it renders on the host driver.
- desktop/packaging/arch/{PKGBUILD,thoughtsync.desktop,README.md}: `makepkg -si`
  installs /usr/bin/thoughtsync + .desktop + icon; deps webkit2gtk-4.1/gtk3/...;
  builds the frontend + `cargo build --release` (no tauri-cli). Uses the host
  graphics stack -> avoids EGL_BAD_PARAMETER.
- Commit the icon set (desktop/src-tauri/icons/*.png, un-gitignored) so BOTH
  `cargo build` (pacman) and `cargo tauri build` (deb/appimage) work without a
  generate step; bundle.icon -> the 4 committed PNGs; drop the `cargo tauri icon`
  step from desktop.yml.
- Broaden the WebKit software-render hardening (lib.rs) to ALL Linux (was
  AppImage-scoped) so the native build also renders if system WebKit is finicky.

Can't CI-test the PKGBUILD (Arch-only; CI is Debian) -- operator builds locally.
desktop.yml re-verifies the deb+AppImage build with the committed icons.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FRgehjoz7Yv8LkUfADxACm

desktop/packaging/arch/PKGBUILD

@@ -0,0 +1,68 @@
+# Maintainer: bvandeusen
+#
+# ThoughtSync desktop (Tauri v2) — native Arch package.
+#
+# Built from THIS repo checkout, from SOURCE, linked against your SYSTEM libraries.
+# That is the whole point: it uses the host's graphics stack (webkit2gtk-4.1 + your
+# GPU driver), which avoids the bundled-AppImage "EGL_BAD_PARAMETER" black window.
+#
+# Usage (from a clone of the thoughtsync repo):
+#   cd desktop/packaging/arch
+#   makepkg -si
+#
+pkgname=thoughtsync-desktop
+pkgver=0.1.0
+pkgrel=1
+pkgdesc="ThoughtSync desktop — local-first Keep-style thought capture"
+arch=('x86_64')
+url="https://git.fabledsword.com/bvandeusen/thoughtsync"
+license=('MIT')
+depends=(
+  'webkit2gtk-4.1'
+  'gtk3'
+  'cairo'
+  'gdk-pixbuf2'
+  'glib2'
+  'libsoup3'
+  'pango'
+  'hicolor-icon-theme'
+  'desktop-file-utils'
+  'librsvg'
+)
+makedepends=('rust' 'nodejs' 'npm' 'git' 'pkgconf')
+# Cargo's release profile already does its own LTO; don't let makepkg inject C-level
+# LTO flags into the crates that build native code.
+options=('!lto')
+
+# Locate the repo root this PKGBUILD lives inside (desktop/packaging/arch/).
+_repo() { git -C "$startdir" rev-parse --show-toplevel; }
+
+pkgver() {
+  cd "$startdir"
+  printf "r%s.%s" "$(git rev-list --count HEAD)" "$(git rev-parse --short HEAD)"
+}
+
+build() {
+  local repo; repo="$(_repo)"
+
+  # 1) Build the shared Vue frontend — it's embedded into the binary at compile time
+  #    (tauri generate_context!), so it must exist before the cargo build.
+  cd "$repo/frontend"
+  npm ci
+  npm run build
+
+  # 2) Compile the native binary against SYSTEM libraries (no bundling, no tauri-cli).
+  cd "$repo/desktop/src-tauri"
+  cargo build --release
+}
+
+package() {
+  local repo; repo="$(_repo)"
+
+  install -Dm755 "$repo/desktop/src-tauri/target/release/thoughtsync-desktop" \
+    "$pkgdir/usr/bin/thoughtsync"
+  install -Dm644 "$repo/desktop/src-tauri/app-icon.png" \
+    "$pkgdir/usr/share/pixmaps/thoughtsync.png"
+  install -Dm644 "$startdir/thoughtsync.desktop" \
+    "$pkgdir/usr/share/applications/thoughtsync.desktop"
+}