v0.1.7 - Thrad bid fallback hardening

Maintenance evidence release for Codex for OSS review.\n\n- Hardened Thrad live-shaped bid normalization.\n- Added OpenRTB-style seatbid/bid payload support.\n- Rejected malformed live payloads without creative instead of manufacturing invalid ad creative.\n- Added timeout, 500, malformed payload, and /v1/thrad/mock-to-/v1/analyze fallback tests.\n- Synced README verification evidence to 110 passing tests.\n- CI and CodeQL are green on this commit; open code-scanning alerts remain 0.