Fix: declare composer autoloader suffix and Psalm cache dir

[Rom1-B]

Checklist before requesting a review

Please delete options that are not relevant.

• I have performed a self-review of my code.
• I have added tests (when available) that prove my fix is effective or that my feature works.
• I have updated the CHANGELOG with a short functional description of the fix or new feature.
• This change requires a documentation update.

Description

• fixes # N/A
• Fixes CI failures by declaring a unique composer autoloader suffix and setting an explicit Psalm cache directory.

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