Fix translation gaps: inline JS, add chart titles, localize period selector (#60)

- Revert sem-localize.js from fetch() to inline translations — eliminates
  async loading issues that caused raw keys showing in tab headers
- Add 11 missing translation keys: ApexCharts titles (Energy Costs,
  Battery 24h, etc.), period selector buttons, production labels
- Localize sem-period-selector-card: Heute/Gestern/Diese Woche/etc.
- Regenerate sem-localize.js from translations.json (149 keys x 6 langs)

Dashboard translation now covers ~95% of visible text:
- Tab headers, section titles, card labels, period buttons — all translated
- ApexCharts titles translated via dashboard_generator.py
- Entity names via translations/*.json

Closes #60

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: belinea4071