translations: add Turkish (tr_TR)

[yeggis]

Summary

Adds Turkish (tr_TR) translation generated with Gemini 2.5 Flash.

The built-in gemini-translate.sh script fails silently when attempting to translate — it sends all ~3878 keys in a single request, which causes Gemini to truncate its output and return invalid JSON. I worked around this by splitting the payload into 700-key chunks and retrying on 429/503 errors, which allowed the translation to complete successfully.

Testing

• inir restart && inir logs — no errors
• UI language switched to tr_TR, shell loaded correctly

Notes

Closes #140

[snowarch]

Thanks @yeggis — appreciated, and good catch on the chunking workaround for the silent truncation. Queued. Since it's machine-translated, a native tr_TR review would be welcome at some point, but it's not a blocker for merging. (ref #140)