Using NLE native plugin system + custom premiere port

[dspury]

Changes

• Added NLE-aware init/config support and vit init --nle premiere
• Added macOS-only vit install-premiere / vit uninstall-premiere
• Simplified Premiere bridge init flow
• Updated install.sh, README.md, and CLAUDE.md for dual-NLE support
• Hardened repo weak points:
  • deterministic main branch init
  • safer clone destination parsing
  • clearer warnings for optional AI / UI fallbacks
  • declared pytest in .[dev]
• Added targeted CLI/core test coverage

Testing

• python -m compileall vit tests resolve_plugin premiere_plugin/premiere_bridge.py
• python -m vit.cli --help
• python -m vit.cli init --help
• smoke checks for branch init, clone destination parsing, and Premiere installer flow

Follow-up

• Windows Premiere install/bootstrap remains out of scope for this PR.

Future Build

A follow-up build will focus on true cross-NLE collaboration for professional post-house
workflows.

Planned direction:

• enable mixed-NLE teams to share the same Vit project safely
• improve cross-NLE fidelity for cuts, color, audio, markers, and effects
• expand Resolve and Premiere serialization/deserialization so shared JSON is a reliable
  interchange layer, not just a shared repo format
• close the remaining gaps around effects, generators/titles, and grade translation between
  Resolve and Premiere
• support workflows such as editing in Premiere, color in Resolve, and finishing across
  departments without breaking project state
• continue expanding installer, validation, and workflow support beyond the current macOS-
  first build