Update API definitions to vMix v29 and add v29 documentation links

[vincentberry]

Summary

This PR updates the API source and the homepage to support the new features in vMix v29. It includes:

• Major update to public/data/api.json: addition and updates of many functions (new v29 commands, version updates for several entries, corrections to notes and structure).
• Update to public/index.html: addition of links to the official v29 documentation.

Key changes

• Notable additions:
  • OMTSelectSourceByIndex, OMTSelectSourceByName (group omt).
  • New OverlayInput5..OverlayInput8 commands (with In/Off/Out/Zoom variants), and OverlayInputXLast.
  • New / revised: PreviewInput, PreviewOverlayInput*, PreviewInputNext/Previous.
  • Replay: many ReplayA/B/C/D... entries, new text management commands (ReplaySetLastEventText*, ReplayAppend*), Replay quad mode (On/Off/Toggle), ReplaySelectNext/Previous/LastEvent, ReplaySetAudioSource, ReplayScrollSelectedEvent, etc.
  • PTZ: movements, zoom, virtual input actions, update virtual input (various additions and updates).
  • Stinger and SetStingerGTInput1..8, Stinger1..8 (GT input assignment and triggers).
  • Cleanup/normalization of certain fields (spacing after ":" in JSON, adjusted versions).
• Modified files:
  • public/data/api.json (extensive changes)
  • public/index.html (added v29 links)