[ci] Switch CI deps to GTK4 / WebKitGTK 6.0

Wails v3 alpha.94 switched its default Linux backend from GTK3 +
WebKit2GTK 4.1 to GTK4 + WebKitGTK 6.0 (the GTK3 path is now gated
behind a `gtk3` build tag). cgo files that the binary, the tests, and
the lint job all parse now request `pkg-config --cflags gtk4
webkitgtk-6.0 ...`, so the existing libgtk-3-dev + libwebkit2gtk-4.1
apt deps no longer satisfy them — lint, unit tests, and the linux
release build all fail with `Package 'gtk4' ... not found`.

Replace the apt deps across the four workflows that build/lint the
client tree (golangci-lint, golang-test-linux, release, and the wasm
lint job that also walks client/) with libgtk-4-dev + libwebkitgtk-6.0-dev
+ libsoup-3.0-dev. Both packages are available from jammy (22.04 LTS)
onwards, so existing ubuntu-22.04 runners stay valid.

.github/workflows/golang-test-linux.yml

@@ -51,7 +51,7 @@ jobs:
 
       - name: Install dependencies
         if: steps.cache.outputs.cache-hit != 'true'
-        run: sudo apt update && sudo apt install -y -q libgtk-3-dev libwebkit2gtk-4.1-dev libsoup-3.0-dev libayatana-appindicator3-dev libgl1-mesa-dev xorg-dev gcc-multilib libpcap-dev
+        run: sudo apt update && sudo apt install -y -q libgtk-4-dev libwebkitgtk-6.0-dev libsoup-3.0-dev libayatana-appindicator3-dev libgl1-mesa-dev xorg-dev gcc-multilib libpcap-dev
 
       - name: Install 32-bit libpcap
         if: steps.cache.outputs.cache-hit != 'true'
@@ -141,7 +141,7 @@ jobs:
             ${{ runner.os }}-gotest-cache-
 
       - name: Install dependencies
-        run: sudo apt update && sudo apt install -y -q libgtk-3-dev libwebkit2gtk-4.1-dev libsoup-3.0-dev libayatana-appindicator3-dev libgl1-mesa-dev xorg-dev gcc-multilib libpcap-dev
+        run: sudo apt update && sudo apt install -y -q libgtk-4-dev libwebkitgtk-6.0-dev libsoup-3.0-dev libayatana-appindicator3-dev libgl1-mesa-dev xorg-dev gcc-multilib libpcap-dev
 
       - name: Install 32-bit libpcap
         if: matrix.arch == '386'

.github/workflows/golangci-lint.yml

@@ -50,7 +50,7 @@ jobs:
           cache: false
       - name: Install dependencies
         if: matrix.os == 'ubuntu-latest'
-        run: sudo apt update && sudo apt install -y -q libgtk-3-dev libwebkit2gtk-4.1-dev libsoup-3.0-dev libayatana-appindicator3-dev libgl1-mesa-dev xorg-dev libpcap-dev
+        run: sudo apt update && sudo apt install -y -q libgtk-4-dev libwebkitgtk-6.0-dev libsoup-3.0-dev libayatana-appindicator3-dev libgl1-mesa-dev xorg-dev libpcap-dev
       - name: Stub Wails frontend bundle
         # client/ui/main.go has //go:embed all:frontend/dist. The
         # directory is produced by `pnpm run build` and is gitignored, so

.github/workflows/release.yml

@@ -360,7 +360,7 @@ jobs:
           version: 9
 
       - name: Install dependencies
-        run: sudo apt update && sudo apt install -y -q libgtk-3-dev libwebkit2gtk-4.1-dev libsoup-3.0-dev libayatana-appindicator3-dev gcc-mingw-w64-x86-64
+        run: sudo apt update && sudo apt install -y -q libgtk-4-dev libwebkitgtk-6.0-dev libsoup-3.0-dev libayatana-appindicator3-dev gcc-mingw-w64-x86-64
 
       - name: Decode GPG signing key
         if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository

.github/workflows/wasm-build-validation.yml

@@ -25,7 +25,7 @@ jobs:
         with:
           go-version-file: "go.mod"
       - name: Install dependencies
-        run: sudo apt update && sudo apt install -y -q libgtk-3-dev libayatana-appindicator3-dev libgl1-mesa-dev xorg-dev libpcap-dev
+        run: sudo apt update && sudo apt install -y -q libgtk-4-dev libwebkitgtk-6.0-dev libsoup-3.0-dev libayatana-appindicator3-dev libgl1-mesa-dev xorg-dev libpcap-dev
       - name: Install golangci-lint
         uses: golangci/golangci-lint-action@4afd733a84b1f43292c63897423277bb7f4313a9 # v8.0.0
         with: