feat(output): compact YouTube and Instagram defaults

[DeanThompson]

Summary

• add compact projection rules for all YouTube and Instagram capabilities
• make search/list defaults table-shaped for agent use instead of raw provider payloads
• drop media/CDN URL fields from default search/list outputs while keeping stable IDs (video_id, media_id, shortcode, channel_id)
• keep full payload available through --output data / --debug

Output policy

• Instagram media lists (search_reels, get_user_posts, get_user_reels) omit media_url, thumbnail, and permalink in compact output
• YouTube video lists (search_videos, get_channel_videos) omit url, thumbnail, and description in compact output
• detail endpoints keep canonical identity and summary fields; transcripts remain pass-through because content is the requested payload

Verification

• go test ./...
• git diff --check