🛡️ 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>

docs/GoogleDriveSetup.md

@@ -30,7 +30,7 @@ End users can authorize their own Google Drive integration directly from the **I
 1. Navigate to `/integrations` and click **+ Add Destination** (or **+ Add Source** for Watch Folder).
 2. Create a Google Drive destination integration (or a Watch Folder with `source_type = google_drive`).
 3. Click the **Authorize** button — it opens the OAuth wizard pre-loaded with your integration's configuration.
-4. If the administrator has configured system-wide Google Drive app credentials (`GOOGLE_DRIVE_CLIENT_ID` / `GOOGLE_DRIVE_CLIENT_SECRET`), the wizard defaults to using them — no need to register your own Google Cloud app. Uncheck the toggle to use custom credentials if needed.
+4. Enter your Google OAuth Client ID and Client Secret in the wizard.
 5. Click **Start Authentication Flow** and authorize access in Google.
 6. Credentials are saved automatically to your personal integration record; the page redirects back to `/integrations`.
 7. Re-authorization is available at any time via the **Re-Authorize** button.