feat(ConfigLoader): add validation for complete configuration before warmUp

[s2x]

Summary

Add validation in warmUp() method to ensure all three config sections (workerman, process, scheduler) are set before writing to cache.

Problem

In the ConfigLoader class, the $config property is populated by three separate setter calls. If the warmUp() method is called before all three sections are set, the saved configuration will be incomplete. There is no validation that all three sections have been set.

Changes

src/ConfigSection.php (new file)

• Add enum ConfigSection with cases: WORKERMAN, PROCESS, SCHEDULER
• Uses string values for clarity

src/ConfigLoader.php

• Add validation in warmUp() method using ConfigSection enum
• Throws LogicException with descriptive message when any config section is missing
• Lists all missing sections (e.g., "Missing: process, scheduler")
• Refactored to use ConfigSection enum instead of magic numbers

tests/ConfigLoaderTest.php (new file)

• 9 comprehensive tests covering:
  • Missing workerman config
  • Missing process config
  • Missing scheduler config
  • Multiple missing sections
  • All sections missing
  • Complete configuration (success case)
  • Getter methods validation

Testing

Unit tests pass:

PHPUnit 10.5.63
OK (9 tests, 21 assertions)

BREAKING CHANGE

Cache format changed from numeric indices to string keys:

• Old format: [0 => ..., 1 => ..., 2 => ...]
• New format: ['workerman' => ..., 'process' => ..., 'scheduler' => ...]

Existing cache must be cleared after upgrade:

rm -rf var/cache/*

Closes #35