feat(DCT-91): map video fields on AITB Dataset

[dessskris]

Adds video_url as a supported AI Task Builder dataset schema field, mirroring the existing audio_url support, and adds a manual test script for the video batch preview flow.

What changed

video_url dataset schema support

• Added video_url to the allowed dataset schema field types
• Updated dataset schema validation errors to include video_url
• Updated aitaskbuilder dataset create --schema help text and inline examples
• Added video_url to docs/examples/dataset-schema.json
• Extended schema validation tests to cover video_url

Video URL validation on dataset upload

• Added validation for video_url columns in both CSV and JSONL uploads
• Rejects unsupported video URLs unless they end with one of:
  • .mp4
  • .mov
  • .webm
• Refactored the audio/video URL validation into shared generic helpers to avoid duplicating the CSV/JSONL scanning logic

Manual test scripts

• Moved scripts/manual-tests/test_audio_batch_preview.go into its own audio_batch_preview subdirectory, since a second package main script can't live alongside it in a flat directory
• Added scripts/manual-tests/video_batch_preview, a manual end-to-end script exercising dataset creation with a video_url field, upload validation, and batch preview

Test plan

• go test ./...
• golangci-lint run
• Manual run of scripts/manual-tests/video_batch_preview against a real workspace confirmed the flow end-to-end

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[Copilot]

Pull request overview

Adds video_url as a first-class typed dataset schema field for AI Task Builder, extending the existing audio_url behavior to dataset schema parsing/validation, dataset upload validation, documentation examples, and manual end-to-end preview testing.

Changes:

• Extend typed dataset schema support to allow video_url (including CLI help text + example schema JSON).
• Add upload-time validation for video_url columns in CSV/JSONL and refactor audio/video URL validation into shared helpers.
• Add a new manual test script for the video batch preview flow and adjust the audio manual script directory structure.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
scripts/manual-tests/video_batch_preview/main.go	New manual end-to-end script for dataset creation/upload + batch preview using video_url.
scripts/manual-tests/audio_batch_preview/main.go	Updates repo-root resolution after moving the audio manual test into a subdirectory.
docs/examples/dataset-schema.json	Adds video_url to the example typed schema.
cmd/aitaskbuilder/upload_dataset.go	Adds video_url upload validation and refactors media URL validation into shared helpers.
cmd/aitaskbuilder/upload_dataset_test.go	Extends tests to cover invalid video_url uploads and JSONL validation.
cmd/aitaskbuilder/dataset_schema.go	Allows video_url as a valid dataset schema field type and updates the invalid-type error message.
cmd/aitaskbuilder/dataset_schema_test.go	Updates schema parsing tests to include video_url.
cmd/aitaskbuilder/create_dataset.go	Updates --schema help text to include video_url in the documented field types.