jpirnay 87d9d1dc2a perf: Improve font drawing performance (#978) ...

## Summary

* ``renderChar`` checked ``is2Bit`` on every pixel inside the inner
loop, even though the value is constant for the lifetime of a single
glyph
* Moved the branch above both loops so each path (2-bit antialiased /
1-bit monochrome) runs without a per-pixel conditional
* Eliminates redundant work in the two inner loops that render font
glyphs to the frame buffer, targeting ``renderChar`` and
``drawTextRotated90CW`` in ``GfxRenderer.cpp``

## Additional Context
* Measured on device using a dedicated framebuffer benchmark (no display
refresh). 100 repetitions of "The quick brown fox jumps".

| Test            | Before          | After           | Change  |
|-----------------|-----------------|-----------------|---------|
| drawText UI12   | 1,337 µs/call | 1,024 µs/call | −23%|
| drawText Bookerly14 | 2.174 µs / call | 1,847 µs/call | −15% |

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### 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? _**PARTIALLY**_ Claude did
the analysis and wrote the benchmarks

2026-02-20 16:39:10 +11:00

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