Fix SSRF bypass via curl callback EventCache corruption

[PopoviciMarian]

The firewall used a global EventCache singleton that was reset at every hook entry. When curl callbacks (CURLOPT_WRITEFUNCTION, etc.) invoked hooked PHP functions like file_put_contents(), nested hooks corrupted the outer hook's context. The POST handler then read empty values and skipped SSRF validation entirely.

Summary by Aikido

Security Issues: 0	🔍 Quality Issues: 4	Resolved Issues: 0

⚡ Enhancements

• Added ScopedEventContext RAII and pushed contexts in handlers automatically.

🐛 Bugfixes

• Fixed SSRF bypass caused by curl callback corrupting EventCache context.

🔧 Refactors

• Replaced global EventCache with EventCacheStack and stack-based contexts.
• Replaced direct eventCache field accesses with eventCacheStack.Top() calls.

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[aikido-pr-checks]

Repeated conditional access pattern 'eventCacheStack.Empty() ? "" : eventCacheStack.Current().' appears across many case branches; centralize into a helper (e.g., GetCurrentEventField(name)) to remove duplication.

Details

✨ AI Reasoning
​Multiple case branches now repeat the exact conditional expression eventCacheStack.Empty() ? "" : eventCacheStack.Current(). to read different EventCache fields. This yields many near-identical lines that perform the same logical operation (get current event field, or empty string if stack empty). Consolidating that access into a small helper would reduce repetition and risk of inconsistent edits across branches.

🔧 How do I fix it?
Delete extra code. Extract repeated code sequences into reusable functions or methods. Use loops or data structures to eliminate repetitive patterns.

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