feat(cli): add image update command for metadata and tags

[digaobarbosa]

Description

Adds CLI support for updating metadata and tags on existing images using the new workspace-level API endpoints (roboflow/roboflow#11836).

Changes:

• New roboflow image update command — single-image sync or multi-image batch (async with polling)
• Refactored roboflow image tag to use the new POST /{workspace}/images/{imageId}/metadata endpoint, removing the now-unnecessary --project flag
• Two new rfapi adapter functions: update_image_metadata (sync) and batch_update_image_metadata (async)

Type of change

• New feature

How has this change been tested?

• 116 unit tests pass (16 new tests covering adapter + CLI handler)
• ruff lint and mypy pass
• CLI help verified for both image update and image tag

Usage examples

# Single image: set metadata + add tags
roboflow image update <image_id> -m '{"camera": "cam1"}' --add-tags "review,v2"

# Batch: update multiple images, poll for completion
roboflow image update img1,img2,img3 --add-tags "processed" --poll

# Tag shorthand (no --project needed anymore)
roboflow image tag <image_id> --add "review" --remove "draft"

Will the change affect Universe?

No

Any specific deployment considerations

N/A — SDK-only change

Docs

• Docs updated? CLI-COMMANDS.md update needed (tracked separately)