Add comprehensive security test suite for TH-03 (plan line 874) verifying
MCP server requires authentication on non-loopback binds.
Test coverage:
- IPv4/IPv6 all-addresses bind requires token (exit 78)
- Loopback addresses (127.0.0.1, ::1, localhost) exempt from auth
- Token auth via PDFTRACT_MCP_TOKEN env var and --auth-token-file
- Atomic failure verification (no listener during failure window)
- Exit code specificity (EX_CONFIG=78, not just any non-zero)
- Parallel bind attempts all fail securely
File: crates/pdftract-core/tests/TH-03-mcp-no-auth.rs (529 lines, 11 tests)
Verification note: notes/pdftract-5m3hp.md
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>