feat(captions): add expressive presentation workflow

[Wandi-Liao]

What changed

• Added Expressive captions with program-wide layout beats, semantic emphasis, and explicit Karaoke review.
• Preserved Standard behavior and extended hash-bound review and protocol validation for dynamic Expressive evidence.

Files changed

M skills/video-add-captions/SKILL.md
M skills/video-add-captions/assets/captions-review.html
M skills/video-add-captions/reference/caption-rules.md
M skills/video-add-captions/scripts/build_caption_review.py
M skills/video-add-captions/scripts/build_captions.py
M skills/video-add-captions/scripts/caption_interaction.mjs
M skills/video-add-captions/scripts/caption_interaction_state.mjs
M skills/video-add-captions/scripts/check_caption_interaction.mjs
M skills/video-add-captions/scripts/check_caption_review.py
M skills/video-add-captions/scripts/check_project_protocol.py
M skills/video-add-captions/scripts/check_structure.ps1
M skills/video-add-captions/scripts/generate_caption_project.mjs
M skills/video-understand/scripts/check_protocol_extensions.py
M skills/video-understand/scripts/projectlib.py

Why it changed

Expressive captions need meaning-aware placement and emphasis while keeping editorial choices reviewable and rendering deterministic.