fix: add SSRF protection and enable TLS verification in URI source

[Joshua-Medvinsky]

Problem

The URI data source passes user-controlled URLs directly to requests.head() and requests.get() with verify=False, enabling SSRF attacks against internal services and cloud metadata endpoints, as well as MITM attacks on outbound connections.

Fix

1. Add _is_private_url() validation function that blocks URLs pointing to private/internal IP ranges (RFC 1918, loopback, link-local, reserved) and known metadata hostnames.
2. Change verify=False to verify=True in get_url_content_type().
3. Raise ValueError when a private URL is detected.

Test Plan

• Existing test suite passes
• URLs with private IPs (127.0.0.1, 10.x.x.x, 169.254.169.254) are rejected
• Public URLs (https://example.com) still work correctly
• TLS verification is enforced on all outbound requests

Security Note

Severity: High — SSRF allows access to internal services and cloud metadata (AWS/GCP/Azure credentials). Disabled TLS verification enables MITM attacks.

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