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/src-tauri/.gitignore

@@ -3,7 +3,3 @@
 
 # Generated by Tauri
 /gen/schemas
-
-# App icons are generated from ../../frontend/public/icon.svg via `cargo tauri
-# icon` (in CI before the build); not committed.
-/icons/

desktop/src-tauri/src/lib.rs

@@ -30,17 +30,11 @@ pub fn run() {
 /// (https://v2.tauri.app/develop/debug/linux-graphics/) is to force the software
 /// fallbacks at startup, before the webview is created, so end users don't have to.
 ///
-/// We apply the fix ONLY for AppImage launches (where these failures cluster and where
-/// bundled libs are in play), leaving each var overridable — native (.deb) installs use
-/// system libs and keep GPU acceleration untouched. WebKit software rendering is plenty
-/// for this UI.
+/// Applied on all Linux launches (this UI doesn't need GPU compositing, and the failure
+/// spans AppImage, native, and dev builds), each var left overridable so a user can
+/// re-enable acceleration by exporting it themselves before launch.
 #[cfg(target_os = "linux")]
 fn harden_linux_webkit_rendering() {
-    let is_appimage =
-        std::env::var_os("APPIMAGE").is_some() || std::env::var_os("APPDIR").is_some();
-    if !is_appimage {
-        return;
-    }
     // Ordered per Tauri's escalation ladder; each set only if the user hasn't chosen.
     for (key, value) in [
         ("__NV_DISABLE_EXPLICIT_SYNC", "1"),

desktop/src-tauri/tauri.conf.json

@@ -37,8 +37,7 @@
       "icons/32x32.png",
       "icons/128x128.png",
       "icons/128x128@2x.png",
-      "icons/icon.icns",
-      "icons/icon.ico"
+      "icons/icon.png"
     ]
   }
 }