feat(config): add error rate limiting

[usernane]

Description

No rate limiting for repeated errors. In high-traffic scenarios, the same error can flood logs.

Implementation Details

• Add HandlerConfig::setRateLimit(int $maxPerMinute)
• Track error signatures (hash of class+line+message)
• Skip handler execution if rate exceeded
• Log "X similar errors suppressed" summary periodically

Example Usage

$config = new HandlerConfig();
$config->setRateLimit(100); // Max 100 of same error per minute
Handler::setConfig($config);

Acceptance Criteria

• Configurable rate limit per error signature
• Duplicate errors suppressed when limit reached
• Summary logged when suppression occurs
• Rate limit resets after time window