Fix Linux launcher missing SONAME mappings (Arch startup crash)

[shreyasmene06]

What this fixes

Fixes Linux launcher startup failures where dependency checks pass but the app still crashes with missing shared libraries.

Closes #57

Root cause

The release launcher script had no package mappings for several runtime SONAMEs required by bundled ffmpeg stack:

• libjxl.so.0.7
• libjxl_threads.so.0.7
• librav1e.so.0
• libSvtAv1Enc.so.1
• librist.so.4

On rolling distros (Arch), newer SONAMEs are present but older SONAMEs are absent, so launch failed even with libraries installed.

Changes

1. Add package mappings for the missing SONAMEs across distro maps
2. Add Arch compatibility symlink fallback in local lib/ for known SONAME bumps (libjxl, libjxl_threads, librav1e, libSvtAv1Enc)
3. Track launcher source in-repo at android_dex_linux/run_android_dex.sh
4. Note launcher script source path in README

Validation summary

After patching, ldd no longer reports unresolved libs for the launcher binary on Arch and the app proceeds to GTK startup instead of exiting with missing library errors.

[persoluna]

My system has:
libjxl 0.12.0
rav1e 0.8.1
svt-av1 4.2.0

ldd reported the missing SONAMEs:
libjxl.so.0.7
libjxl_threads.so.0.7
librav1e.so.0
libSvtAv1Enc.so.1
librist.so.4

After investigating with readelf, objdump, and LD_DEBUG=libs, the startup failure matched the root cause described in this PR.
One question: the PR adds compatibility symlinks for older SONAMEs. Have you been able to test the application beyond startup on Arch (screen mirroring, recording, etc.)? I'm curious whether the newer libraries are ABI-compatible enough in practice, or whether a future rebuild against current libraries is planned