[translation] Translate README to Turkish

[mccarthy606]

The current README.tr.md is a stub. Replace it with a full Turkish translation of README.md.

What to do

1. Read the current English README.md
2. Replace README.tr.md with a full Turkish translation
3. Keep the language nav row (only **Türkçe** should be unlinked, others linked)
4. Same structure as English version: Contents → What this is → The Stack → 7 products → Quick Start → What's Inside → The Operator Playbook → Why this exists → Acknowledgements → Status → License
5. Keep code blocks and command examples in their original form
6. Use natural Turkish, not literal translation

Reference

README.es.md and README.ru.md are full translations to crib structure from.

Effort: ~2-3 hours.