add: Turkish (Türkçe) language support

[whynasil]

Summary

• Add Turkish (Türkçe) translation file (src/i18n/tr.ts)
• Register Turkish in the i18n module (src/i18n/index.ts)
• Users can now select Türkçe as their interface language via BOT_LOCALE or in the config wizard

[grinev]

@whynasil thanks for your contribution. Please follow the instructions here: https://github.com/grinev/opencode-telegram-bot/blob/main/docs/LOCALIZATION_GUIDE.md
You need to update README.md

[grinev]

@whynasil I don't know Turkish so I asked GPT 5.4 to check. Here is some comments:

1. src/i18n/tr.ts:112
   tts.disabled contains broken encoding: devre dışı bırak��ldı. This should be fixed before merge.
2. src/i18n/tr.ts:20 and src/i18n/tr.ts:200
   Arayecekler does not look like valid Turkish here. These strings are for the agents list, so the wording should be corrected.
3. src/i18n/tr.ts:159 and src/i18n/tr.ts:167
   The text still contains the English word retry (/abort retry edin). This looks untranslated / unnatural and should be localized properly.
4. src/i18n/tr.ts:254
   permission.name.webfetch is translated as Web İndir, which sounds like “download from the web” rather than “fetch web content”. The meaning is misleading for this permission label.
5. src/i18n/tr.ts:210
   model.menu.recent_title is 🕘 Son, which reads incomplete/awkward as a section title. It should be replaced with a proper Turkish equivalent for “Recent”.
6. src/i18n/tr.ts:430
   There is a visible typo in Gerçik durum kontrolleri. This should be corrected.

At least please fix the first one, as for the other points, see for yourself whether edits are required or not.

[grinev]

Also pls rebase your branch and remove cli.* keys