[Code Quality] Add property type declarations to IdpTokenRefresher.php

[cbcoutinho]

Context

From PR #401 code review - Low priority code quality improvement.

Problem

IdpTokenRefresher.php class properties lack type declarations, which are supported in PHP 7.4+.

Current Code:

class IdpTokenRefresher {
    private $config;
    private $httpClient;
    private $logger;
    private $mcpServerClient;

Proposed Improvement:

class IdpTokenRefresher {
    private IConfig $config;
    private IClient $httpClient;
    private LoggerInterface $logger;
    private McpServerClient $mcpServerClient;

Benefits

• Better IDE autocomplete and type checking
• Catches type errors at development time
• Improves code documentation
• Aligns with modern PHP standards

Implementation Notes

• Verify Nextcloud's minimum PHP version supports typed properties (PHP 7.4+)
• Add return type declarations to methods as well
• Consider using strict_types declaration at file level

References

• File: third_party/astrolabe/lib/Service/IdpTokenRefresher.php
• Related to PR feat(astrolabe): Nextcloud app UI with PDF viewer, webhooks, and OAuth refresh #401 code review
• PHP Typed Properties: https://www.php.net/manual/en/language.types.declarations.php

Priority

Low - Code quality improvement, no functional change