explore: use class-specific tab labels in item details only (Fixes #6395)

[XinyuYangYXY]

Description (required)

Fixes #6395

What changes did you make and why?

Problem
The Item (Wikidata) details screen showed category-oriented labels (“Subcategories / Parent categories”) where class hierarchy labels are expected (“Child classes / Parent classes”). A prior attempt mistakenly changed global strings, which caused category flows (e.g., searching "rabbit" → open a category) to display the wrong labels.

Approach

• Scope labels to the correct context
  • In WikidataItemDetailsActivity, set tabs to use class-specific resources:
    title_for_child_classes → child tab,
    title_for_parent_classes → parent tab.
• Keep categories unchanged
  • Do not rename or repoint category strings; category screens continue to use title_for_subcategories / title_for_parent_categories.
• Clean up strings
  • Remove duplicate keys introduced earlier and ensure unique resource names for classes vs categories.
• Repository hygiene
  • Rebased on latest upstream main.
  • Deleted incorrect string edits from the previous attempt to avoid regressions.

Tests performed (required)

• Build variant: 6.0.2-debug-main~4ed9ad508
• Device: Android 15 (API 35) Emulator (Medium Phone)

Manual checks

1. Category context: expolre → search sth. (e.g.,"rabbit") → tab CATEGORIES→ choose one→ read ““Subcategories / Parent categories””.
2. Item context: expolre → search sth. (e.g.,"rabbit") → tab ITEMS→choose one → read “Child classes / Parent classes”.

Before:

1. category

2. item

After:

1. category:

2. item:

[github-actions]

✅ Generated APK variants!

• 🤖 Download betaDebugAPK
• 🤖 Download prodDebugAPK

[nicolas-raoul]

Looks good to me, thanks!