feat(xai): add Grok Imagine video generation (/v1/videos) + CLI
Async video job proxy mirroring the existing image-generation layer split:
Next routes → src/sse/handlers/videoGeneration.js (auth gate, account
fallback loop, refresh persistence) → open-sse/handlers/videoCore.js
(transparent upstream proxy, 401 refresh-once/retry-once, secret sanitization).
- POST /v1/videos/{generations,edits,extensions}: byte-exact body forward
(JSON + multipart), request_id passthrough, Idempotency-Key forwarded
- GET /v1/videos/{request_id}: status/progress/video.url passthrough
- Register grok-imagine-video (kind: "video"); add "video" to MODEL_TYPE_TO_KIND
so video models stay out of chat lists (also fixes runwayml leak)
- 9router xai video CLI: submit → poll → atomic MP4 download
- No auto-retry of creation POSTs (billable jobs); rotate accounts only on
401/403/429; sanitize Bearer tokens + credential values from errors/logs
Closes #1285
d6761c6fb0