refactor(HTTP): split setCURLOptions into category helper methods to reduce complexity

[gr8man]

Description

This PR refactors the massive setCURLOptions() method in CodeIgniter\HTTP\CURLRequest (which was a 180+ line method with extremely high cyclomatic complexity) by splitting it into 8 domain-specific private helper methods. This change adheres to the Single Responsibility Principle (SRP) and the Open-Closed Principle (OCP), making the options-building logic significantly cleaner, easier to read, and simpler to maintain without introducing any backward compatibility (BC) breaks.
Additionally, static analysis (PHPStan Level 6 with strict rules) and test validation have been integrated for all newly created helper methods.

Proposed Changes

• system/HTTP/CURLRequest.php:
  • Extracted configuration building logic from setCURLOptions() into:
    • applyAuthOptions()
    • applySslOptions()
    • applyProxyOptions()
    • applyDebugOptions()
    • applyRedirectOptions()
    • applyConnectionOptions()
    • applyPayloadOptions()
    • applyMiscOptions()
  • Replaced legacy empty() checks with strict comparison operators (isset(), !== '', etc.) inside the new helper methods to comply with strict PHPStan rules.
  • Added full PHPDoc type annotations for arrays (solving missingType.iterableValue warnings).
• tests/system/HTTP/CURLRequestTest.php:
  • Added direct reflection-based unit tests (testApply*Direct) using getPrivateMethodInvoker for all 8 helper methods to ensure maximum test coverage.
  • Adjusted float assertions from assertSame to assertEqualsWithDelta to satisfy Rector rules.
• utils/phpstan-baseline/empty.notAllowed.neon:
  • Updated the baseline count for allowed empty() constructs for CURLRequest to match the new strict refactoring.

Checklist

• All unit tests pass successfully (OK (100 tests, 269 assertions)).
• PHPStan analysis passes with no errors ([OK] No errors).
• Rector analysis passes with no errors.
• Code formatting conforms to project standards (php-cs-fixer).
• No changelog entry added (refactoring only, as there are no real changes for end users).