qt6: add initial version for building and packaging base of Qt6 - #65

Checking PR #65: qt6: add initial version for building and packaging base of Qt6 (Formalities Audit)

✅ Pull request originates from a dedicated feature branch (mirko/add-qt6base)

Commit 2a3b2e7 - qt6: add initial version for building and packaging base of Qt6:

✅ Author and committer identities are valid
✅ Commit is not a merge commit
✅ Commit subject layout and length are valid: "qt6: add initial version for building and packaging base of Qt6"
✅ Commit description lines adhere to width formatting rules
✅ Commit contains a valid 'Signed-off-by:' line matching author or committer
⚠️ Warning: Subject line exceeds soft limit (63/60 chars)
⚠️ Warning: No reference link (e.g., upstream release notes, changelog, or history URL) detected in description.
⚠️ Warning: Commit is unsigned or cryptographic signature verification failed (Reason: unsigned). Signing commits is a recommended best practice for verifying identity, but is not mandatory.