Add IBM Plex Sans Arabic font theme for Arabic readers

[alfarhan]

Thank you

First of all, thank you so much for the incredible work on Papyrix and especially for supporting the Arabic language. The original Xteink firmware had no proper Arabic support, and what you've built here is a game-changer for Arabic readers. We really appreciate it.

Summary

This PR adds IBM Plex Sans Arabic as an alternative Arabic font option alongside the existing Noto Sans Arabic.

• Why IBM Plex Sans Arabic? It has excellent coverage of Arabic Presentation Forms-B (140/144 glyphs vs 89/144 for some other Arabic fonts), which means fewer missing characters when Papyrix's Arabic shaper renders contextual letter forms. It also has a clean, modern look that's very comfortable for long Arabic reading sessions on e-ink.
• The font is licensed under OFL (Open Font License), same as the existing fonts.
• Includes both Regular and Bold weights across all 4 reader sizes (12, 14, 16, 18pt).
• Converted with --arabic flag plus --additional-intervals "0xFB50,0xFDFF" for Arabic Presentation Forms-A coverage.

You may also consider this as a candidate to replace or complement the current default Arabic font if you find the rendering quality better.

Changes

• Added docs/examples/light-ibm-plex-arabic.theme
• Added pre-converted .epdfont files in docs/examples/fonts/ibm-plex-arabic-{12,14,16,18}/
• Updated docs/fonts.md with IBM Plex Sans Arabic entry

Test plan

• Tested on Xteink X4 hardware with Papyrix firmware
• Verified Arabic text renders correctly with minimal missing glyphs
• Tested both Regular and Bold weights
• Confirmed theme loads correctly via Settings > Reader > Theme

🤖 Generated with Claude Code

[faisal1400ab]

hi
is there a bin file to try it
thanks

[alfarhan]

papyrix-ibm-plex-arabic.zip
i uploaded the themes and fonts @faisal1400ab

[faisal1400ab]

thank you so much
will try it