Add Gradio web interface and dictionary builder (Phase 6 prototype)

[vassamag]

This PR adds two files implementing Phase 6 (Web/API) from the roadmap:

build_dictionary.py

• Downloads NM-development/nmd-ce-ru-171k-v0 dataset from HuggingFace
• Builds a local SQLite database (171,204 che-ru pairs)
• Splits into words (80,404), phrases (25,312), sentences (65,488)
• Verified correct by a native Chechen speaker

app.py

• Gradio web interface with three tabs:
  1. Translator (Google Translate, rus/eng ↔ che)
  2. Dictionary search (Matsiev dataset, click row → TTS playback)
  3. TTS (Meta MMS synthesis)
• Runs locally with: python app.py → http://127.0.0.1:7860

[vassamag]

Ассалам Iалайкум! Аша ара баьккхана някъ Iаламата халкъана оьшуш а пайдяхьа а някъ бу! Дела реза хуьлда шуна! Дала аьтто а бойла шу.