🛡️ Sentinel: [MEDIUM] Add input length limits to prevent DoS

[ManupaKDU]

🛡️ Severity: MEDIUM
💡 Vulnerability: Missing input length limit on IP addresses
🎯 Impact: Potential resource exhaustion (DoS) via ipaddress parsing of massively long strings
🔧 Fix: Added strict type and length verification (<= 100 characters) before logging or parsing IP addresses.
✅ Verification: Added test_is_reachable_ip_length_limit unit test, covering the new limits successfully.

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PR created automatically by Jules for task 9768093641647133193 started by @ManupaKDU

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