Major rewrite of help rendering:
- Embed mode (default): Rich embeds with interactive View buttons
(⏮◀️▶️⏭) + category select dropdown + close button
- CV2 mode (when `cv2 toggle` is on): Components V2 containers
with the same navigation
- Shared data-gathering layer: both modes use the same logic to
gather commands, filter permissions, handle categories
- All Red help features: command filtering, permission checks,
aliases, subcommands, cooldowns, format_help_for_context
- Text fallback for DMs
d39ab05676