🛡️ Sentinel: [CRITICAL] Fix SSRF vulnerability in web_fetch tool

[mudcube]

• 🚨 Severity: CRITICAL
• 💡 Vulnerability: web_fetch allowed requesting arbitrary internal endpoints or localhost via direct or redirect-based SSRF.
• 🎯 Impact: Attackers could read internal network resources or cloud metadata.
• 🔧 Fix: Implemented manual DNS resolution, explicit filtering of private/local/unspecified IP ranges, manual redirect tracking (limit 5), and IP pinning using reqwest's resolve to prevent TOCTOU DNS rebinding.
• ✅ Verification: Ran cargo test -p mill-plugin-system to ensure functionality.

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PR created automatically by Jules for task 14048877648785991600 started by @mudcube

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Block shared-address IPv4 ranges

The new SSRF gate still falls through to true for 100.64.0.0/10. When web_fetch is run on a host with services reachable on a CGNAT/overlay range, such as Tailscale addresses, or a metadata service exposed there, an attacker can supply a URL whose DNS result is in that range and the request will be pinned and sent, so the internal-resource read remains possible. This allowlist should reject shared-address/non-global IPv4 ranges before the final allow.

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