[Web] Translate measurement descriptions in ObjectTutorialModal

[mustafa-5493]

📝 [Web] Translate measurement descriptions in ObjectTutorialModal

Description

Follow-up to #292. Short measurement labels (Slope, Width, etc.) are already localized via the object.<TYPE>.measurement.<key>.label namespace introduced in #534. The long-form description strings , the plain-language explanation of why each threshold matters, rendered inside ObjectTutorialModal still live in English in objectTypeConfig.js and were intentionally deferred.

There are roughly 25 descriptions across 9 object types. They're long-ish prose (one sentence each) but mechanical to translate.

Feature / Task Details

• Add object.<TYPE>.measurement.<key>.description entries to en.json and tr.json for every measurement currently defined in objectTypeConfig.js.
• Extend localizeObjectType to translate description (parallel to how it translates label), falling back to the config's English description for any missing key.
• Drop the deferral note in objectTypeConfig.js's docstring (or update it to point at the new keys).
• No new tests strictly required , fall-through covers any missed keys, and existing tests stay green.

Deliverables

• Updated frontend/src/utils/objectTypeConfig.js (extend localizeObjectType)
• Updated frontend/src/i18n/locales/en.json and tr.json

Acceptance Criteria

• Opening "How to measure" on any object in TR shows Turkish descriptions
• EN mode is identical to before
• Missing-key fallback still shows the English description from the config
• All existing tests pass