fix: harden timer total and settings flows

[crisgamat]

Summary

• fix Timer Total Harvest H0400 failures with compatibility fallbacks and safer query handling
• normalize action settings/defaults and stabilize action refresh intervals across setting changes
• improve Forecast compatibility (new + legacy endpoints/headers) and add optional Forecast API token in Status settings
• update documentation in English (README.md) and add CHANGELOG.md

What changed

• Harvest API layer
  • use standard User-Agent format for Harvest requests
  • include API error response text in raised errors
  • use YYYY-MM-DD dates for time_entries range queries
  • add fallback strategy for H0400: retry without user_id, then per-day requests
  • ensure fallback results are filtered to current user
• Stream Deck action behavior
  • avoid duplicate intervals and clean them up on action disappear
  • restart update intervals when settings change
  • apply normalized defaults for missing/invalid settings
• Property Inspectors
  • refresh task dropdown reliably when timer credentials change
  • set How To buttons to type=button to prevent accidental form submit
  • add optional Forecast API Token field to Status action
• Forecast API
  • support modern api.forecast.it and legacy api.forecastapp.com paths
  • support header variants for account compatibility
  • update Forecast web links to app.forecast.it
• Display
  • fix pie chart completion math
• Docs
  • improve setup/build/troubleshooting in README.md
  • add CHANGELOG.md (Keep a Changelog format)

Tests

• npm run build
• npm test -- --runInBand test/common.test.ts test/display.test.ts test/status.test.ts test/settings-normalization.test.ts test/harvest-query-format.test.ts test/harvest-fallback.test.ts