🛡️ Sentinel: Fix zip bomb DoS vulnerability & limit pack import size

[TheDragonSoft]

🛡️ Sentinel Security Report

• 🚨 Severity: MEDIUM / HIGH (Denial of Service / Uncontrolled Resource Consumption)
• 💡 Vulnerability: Unbounded decompressed reading of info.json zip entries in mod_store.rs and downloader.rs allowed zip bombs to trigger Out-Of-Memory (OOM) process crashes. Additionally, Base64 pack imports lacked string length limits.
• 🎯 Impact: Malicious or corrupted mod zip files or oversized pack code inputs could crash the Axial application process by consuming gigabytes of RAM.
• 🔧 Fix: Applied entry.by_ref().take(MAX_INFO_JSON_SIZE) (2 MB) to limit zip decompression reads safely, and enforced MAX_PACK_CODE_LEN (1 MB) on Base64 pack imports.
• ✅ Verification: Added unit tests verifying rejection of oversized pack imports and bounded info.json decompression. All 142 Rust unit tests passed and frontend built cleanly.

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PR created automatically by Jules for task 356014775587353382 started by @TheDragonSoft

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