fix(ci): install xdg-utils for Linux AppImage bundling

The ubuntu-22.04-arm runner image does not preinstall xdg-utils, so
AppImage bundling fails with 'xdg-open binary not found'. Add it to
every Linux system-dependency list in ci.yml and release.yml (the
release ARM job shares the same list and would have failed identically
at tag time).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -221,7 +221,8 @@ jobs:
             libasound2-dev \
             libssl-dev \
             patchelf \
-            librsvg2-dev
+            librsvg2-dev \
+            xdg-utils
 
       - name: Install Rust
         uses: dtolnay/rust-toolchain@29eef336d9b2848a0b548edc03f92a220660cdb8 # stable

.github/workflows/release.yml

@@ -83,7 +83,8 @@ jobs:
             libasound2-dev \
             libssl-dev \
             patchelf \
-            librsvg2-dev
+            librsvg2-dev \
+            xdg-utils
 
       - name: Install Rust
         uses: dtolnay/rust-toolchain@stable
@@ -211,7 +212,8 @@ jobs:
             libasound2-dev \
             libssl-dev \
             patchelf \
-            librsvg2-dev
+            librsvg2-dev \
+            xdg-utils
 
       - name: Install Rust
         uses: dtolnay/rust-toolchain@stable