🛡️ Sentinel: [HIGH] Fix Server-Side Request Forgery in IMAP connections

🚨 Severity: HIGH
💡 Vulnerability: User-provided IMAP `host` in `_test_imap_connection` and `pull_inbox` was not validated against private IPs, creating an SSRF risk.
🎯 Impact: Attackers could abuse the endpoints to port-scan or interact with internal/private network services.
🔧 Fix: Integrated `is_private_ip` from `app.utils.network` to block connections resolving to private, loopback, link-local, or reserved IPs.
✅ Verification: Ran `test_imap_tasks.py` and `test_api_imap_accounts.py` successfully. Checked `ruff` output and diffs. Removed all scratch files from the commit.

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

frontend/templates/files.html

@@ -904,7 +904,7 @@
 
     function viewFileDetail(fileId, event) {
       if (event) event.stopPropagation();
-      window.location.href = `/files/${fileId}`;
+      window.location.href = `/files/${fileId}/detail`;
     }
 
     // ── Preview modal ──