ScriptKit v1.3.0: help system improvements, version date tracking, whatsnew

- help command: inline topics replaced with Browse Topics button
- help auto-injected commands: whatsnew, gen-help, gen-dev-docs (conditional)
- man topics show handout anchor link
- !scriptkit whatsnew [date]: consolidated view across all plugins
- Per-plugin whatsnew accepts date argument
- Version date tracking: changelog dates stored in state, auto-stamp current version
- Shared parseDate/getRelevantChangelog helpers
- Added 1.0.0 changelog entry with date