[codex] Fix Linux WebView release packaging

[filipeborato]

Summary

Fixes the cross-platform WebView setup and makes the Linux release path reproducible locally and in GitHub Actions.

What changed

• Uses WebView2 only on Windows, allowing JUCE to use the default platform WebView on Linux/macOS.
• Updates project metadata and workflow artifact names to version 0.1.2.
• Adds Linux release/install scripts that build VST3, LV2, and Standalone and package full plugin bundles.
• Reworks the Linux GitHub Actions job to call scripts/release-linux.sh --install-deps instead of duplicating packaging logic.
• Publishes Linux-named artifacts: Picotado-v<version>-Linux-VST3.tar.gz, Picotado-v<version>-Linux-LV2.tar.gz, and INSTALL-Linux.md.
• Ignores local dist/ artifacts.

Root cause

The editor forced JUCE's WebView2 backend unconditionally. That is correct for Windows, but Linux needs WebKitGTK and macOS needs WKWebView/default. Forcing WebView2 outside Windows can produce a blank or failed WebView even when the plugin binary builds.

Validation

• Ran scripts/release-linux.sh locally once to completion.
• Confirmed dist/Picotado-v0.1.2-Linux-VST3.tar.gz contains Picotado.vst3/Contents/x86_64-linux/Picotado.so.
• Confirmed the generated VST3 binary is an x86-64 ELF shared object.
• User verified the Linux DAW loads the GUI/WebView correctly after the WebView backend fix.

Notes

The LV2 helper can take a long time during LTO and was given a 20 minute timeout in the Linux release script so CI fails clearly instead of hanging indefinitely.