Fix installable release ZIP and Vite manifest for 3.2.2

[PrestaSafe]

A push to main will publish prettyblocks-{version}.zip with a single prettyblocks/ directory and the compiled Vite manifest at prettyblocks/build/manifest.json. The module reads this visible manifest first and retains support for the previous .vite/manifest.json location.

The release workflow now installs the exact downloaded build artifact on PrestaShop 8.2 and 9.1 before publishing it, validates the manifest entry and assets, and publishes a portable SHA-256 checksum. Release notes and the README distinguish the installable asset from GitHub's automatically generated source archive. The module version is bumped to 3.2.2 so this correction creates a new release.

Validation completed locally:

• Built the versioned ZIP and verified its unique prettyblocks/ root, module version, manifest, and bundled assets.
• Installed that exact ZIP on PrestaShop 8.2.7 / PHP 8.1.33 and PrestaShop 9.1.4 / PHP 8.5.0; installation, activation, routes, PHP syntax, dependencies, and asset HTTP checks passed.
• Shell/PHP syntax checks and git diff --check passed.

Merging into main will trigger publication of release 3.2.2 after the workflow succeeds.