fix(go): added fieldcount boundation checks

[ayush00git]

Why?

Malicious payloads could specify a massive fieldCount, causing the runtime to attempt an unbounded memory allocation.
Deeply nested schema definitions (like a LIST of LIST...) could trigger unbounded recursion, exceeding the goroutine stack limit and crashing the process.

What does this PR do?

Added a hard limit of 10,000 fields and a buffer-remaining check in decodeTypeDef to prevent massive slice allocations.
Added a depth parameter to readFieldType and readFieldTypeWithFlags, capping nested schema definitions at a maximum depth of 64.

Related issues

#3619

AI Contribution Checklist

• Substantial AI assistance was used in this PR: yes / no
• If yes, I included a completed AI Contribution Checklist in this PR description and the required AI Usage Disclosure.
• If yes, my PR description includes the required ai_review summary and screenshot evidence of the final clean AI review results from both fresh reviewers on the current PR diff or current HEAD after the latest code changes.

Does this PR introduce any user-facing change?

• Does this PR introduce any public API change?
• Does this PR introduce any binary protocol compatibility change?

Benchmark

[ayush00git]

@chaokunyang i'm planning to create these bounds configurable, moving them to the Config.