refactor(Helper,TokenManager): migrate guest cookie access to IRequest add typing throughout

[joshtrichards]

• Target version: main

Summary

Moves guest-name cookie access off the $_COOKIE superglobal and onto the injected IRequest service, and modernizes Helper and TokenManager with new typing/docs/etc.

Changes

lib/Helper.php

• Add declare(strict_types=1)
• Add type hints to constructor (?string $userId) and all method signatures
• Refactor parseFileId(): cleaner logic, throw \InvalidArgumentException instead of \Exception (all call sites either already capture this via "catch-all" \Exception handling or already let it bubble up so should be a non-issue) , add explode limit for correctness, add typed array shape to @return
• Null-check preg_replace result in getNewFileName() to avoid silent failure
• Remove getGuestNameFromCookie() (moved to TokenManager which was the only caller anyway)
• Add/improve docblocks throughout

lib/TokenManager.php

• Inject IRequest via constructor
• Move getGuestNameFromCookie() here as a private method using IRequest::getCookie() instead of $_COOKIE
• Add missing return types (Wopi, string, void)
• Reformat long method signatures (one parameter per line)
• Clean up redundant docblock tags where type hints are now explicit

TODO

• Test / see what I broke

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Documentation (manuals or wiki) has been updated or is not required