[codex] Onboard new KIE models and pricing

[gateway]

Summary

Onboards the current KIE model/pricing work so Media Studio can consume it from main after merge.

• Adds seedance-2.0-mini with provider model bytedance/seedance-2-mini, shared Seedance request handling, prompt preset coverage, and observed site pricing.
• Adds kling-3.0-turbo-i2v with provider model kling/v3-turbo-image-to-video, Turbo-specific prompt preset, payload coverage, and observed 720p/1080p per-second pricing.
• Adds the Kling 2.6 motion-control model/preset/pricing work that was already in the local tree, including validation/payload/pricing coverage.
• Updates packaged model specs, packaged prompt profiles, pricing snapshots, pricing refresh mapping, docs, and regression tests.

Safety / publishing scope

No API keys or local machine paths were staged. The staged scan only found documented environment variable names/placeholders such as KIE_API_KEY, not credentials. The included docs changes are public model capability notes, not internal development notes.

Validation

• git diff --check --cached
• git diff --cached | rg -n "(sk-[A-Za-z0-9]|AIza|ghp_|github_pat_|BEGIN (RSA|OPENSSH|PRIVATE)|KIE_API_KEY=|Bearer [A-Za-z0-9_\\-]{20,})" || true
• .venv/bin/python scripts/sync_packaged_specs.py --check
• .venv/bin/python -m pytest -q

Result: 205 passed, 6 skipped.