feat: add Russian narration and subtitle support

[web3blind]

Summary

• add lang: 'ru' as a first-class narration mode
• detect Cyrillic narration and select Edge TTS ru-RU-DmitryNeural in TTS_ENGINE=auto
• preserve spaces when joining Russian subtitle chunks for synthesis
• add bundled-font Cyrillic width metrics in Python and TypeScript
• add a 40-character Russian subtitle budget and a Russian-specific safe layout above the progress bar
• update build, storyboard, typography, and QC guidance for Russian projects
• add reproducible Python and TypeScript regression tests

Validation

• python -m unittest discover -s tests -p 'test_*.py' -v — 4 tests passed
• cd template && npm run typecheck — passed
• cd template && npm run test:russian — passed
• generated a fresh project from the updated template — passed
• generated real Russian Edge TTS audio and timeline from generic test narration — passed
• rendered and visually checked Russian subtitle stills — no clipping, broken glyphs, or progress-bar overlap
• git diff --check — passed

Notes

• Edge TTS is cloud-based and sends narration text to Microsoft; the documentation recommends a local engine or user-provided WAV for sensitive material.
• The bundled Noto Sans SC font contains the Russian alphabet including ё, but not ₽; the documentation recommends spelling out the currency or verifying a fallback font.