feat: Support for kerning and ligatures (#873)

## Summary

**What is the goal of this PR?**
Improved typesetting, including
[kerning](https://en.wikipedia.org/wiki/Kerning) and
[ligatures](https://en.wikipedia.org/wiki/Ligature_(writing)#Latin_alphabet).

**What changes are included?**
- The script to convert built-in fonts now adds kerning and ligature
information to the generated font headers.
- Epub page layout calculates proper kerning spaces and makes ligature
substitutions according to the selected font.


![3U1B1808](https://github.com/user-attachments/assets/1accb16f-2f1a-41e5-adca-89f1f1348494)

![3U1B1810](https://github.com/user-attachments/assets/2f6bd007-490e-420f-b774-3380b4add7ea)

![3U1B1815](https://github.com/user-attachments/assets/1986bb77-2db0-46e2-a5d6-8315dae9eb19)

## Additional Context

- I am not a typography expert. 
- The implementation has been reworked from the earlier version, so it
is no longer necessary to omit Open Dyslexic, and kerning data now
covers all fonts, styles, and codepoints for which we include bitmap
data.
- Claude Opus 4.6 helped with a lot of this.
- There's an included test epub document with lots of kerning and
ligature examples, shown in the photos.

**_After some time to mature, I think this change is in decent shape to
merge and get people testing._**

After opening this PR I came across #660, which overlaps in adding
ligature support.

---

### AI Usage

While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.

Did you use AI tools to help write this code? _**YES, Claude Opus 4.6**_

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/EpdFont/EpdFontFamily.cpp

@@ -26,4 +26,12 @@ const EpdFontData* EpdFontFamily::getData(const Style style) const { return getF
 
 const EpdGlyph* EpdFontFamily::getGlyph(const uint32_t cp, const Style style) const {
   return getFont(style)->getGlyph(cp);
-};
+}
+
+int8_t EpdFontFamily::getKerning(const uint32_t leftCp, const uint32_t rightCp, const Style style) const {
+  return getFont(style)->getKerning(leftCp, rightCp);
+}
+
+uint32_t EpdFontFamily::applyLigatures(const uint32_t cp, const char*& text, const Style style) const {
+  return getFont(style)->applyLigatures(cp, text);
+}