fix(release): strip bundled Wayland libraries from AppImage

[KtzeAbyss]

Problem

The Linux AppImage bundles the build host's libwayland-client, libwayland-cursor, libwayland-egl, and libwayland-server. On hosts with newer Mesa, WebKit can load these incompatible bundled libraries and fail EGL initialization, leaving the application window blank.

The v1.1.6 AppImage still contains all four libraries.

Fix

• add a focused Linux AppImage post-processing script
• pin appimagetool 1.9.1 and verify its published SHA-256 checksum
• preserve the original AppImage runtime while rebuilding the AppDir
• remove every bundled usr/lib/**/libwayland-*.so*
• re-extract the rebuilt image and fail if the libraries remain or the launchers are missing
• discard the stale updater signature and re-sign the final AppImage with the existing Tauri signing key

The .deb and .rpm artifacts and application runtime code are unchanged.

Validation

• processed the published v1.1.6 AppImage: 4 bundled Wayland libraries before, 0 after
• successfully re-extracted the rebuilt x86-64 AppImage with executable AppRun and AppRun.wrapped
• verified stale signatures are removed and the exact workflow signer command generates a new .sig with a temporary Tauri key
• verified a second processing attempt fails safely without changing the image or existing signature
• bash -n scripts/release/postprocess-linux-appimage.sh
• ShellCheck 0.11.0
• actionlint 1.7.12
• git diff --check
• node scripts/check-mirror.mjs

Closes #128

[su-fen]

感谢佬的PR，这个问题还真没仔细研究