feat: add Arabic search ranges and Android highlighting

[Khalid567-CPU]

Summary

Implements the core ArabicKit 0.2.0 search-range and highlighting work tracked in #3.

Included

• ArabicMatchRange for original-source offsets.
• Normalization with UTF-16 source index mapping.
• ArabicSearch.findFirst(...).
• ArabicSearch.findAll(...).
• Optional overlapping matches.
• Correct ranges across diacritics, Quranic marks, tatweel, alef normalization, alef maksura normalization, whitespace normalization, and Latin lowercase expansion.
• Android SpannableString highlighting helpers.
• Updated XML sample app.
• Comprehensive search-range unit tests.
• English and Arabic documentation updates.

Local verification

• clean verifyFoundation :arabickit:assembleRelease
• Result: BUILD SUCCESSFUL
• Gradle exit code: 0
• Generated AAR: arabickit-release.aar (20,635 bytes)
• Working tree clean.

Closes #3