Add Azerbaijani language names and locale strings

[jamalkamaladdin]

This PR adds an Azerbaijani (az-AZ) translation.

New file public/intl/language/az-AZ.json: 182 strings, all filled in.
New file public/intl/messages/az-AZ.json: 529 strings, all filled in.
src/lib/lang.ts: added az-AZ to the language switcher, dateLocale from date-fns az.

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[greptile-apps]

Greptile Summary

Adds complete Azerbaijani localization support.

• Adds Azerbaijani UI messages with matching keys and formatting placeholders.
• Adds Azerbaijani names for supported languages.
• Registers az-AZ in the language selector with the corresponding date-fns locale.

Confidence Score: 5/5

The PR appears safe to merge with complete and consistently registered Azerbaijani localization resources.

No actionable failures remain; both catalogs match their canonical key contracts, formatting placeholders are preserved, and locale registration resolves to valid resources and date formatting support.

Important Files Changed

Filename	Overview
public/intl/language/az-AZ.json	Adds a complete Azerbaijani language-name catalog with canonical key parity.
public/intl/messages/az-AZ.json	Adds a complete Azerbaijani UI catalog with matching ICU placeholders and rich-text tags.
src/lib/lang.ts	Registers Azerbaijani using an available date-fns locale and matching translation resources.

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