feat: extended flex layout

[rauhryan]

What does this PR do?

Adds a slop spike to explore expanding flex sizing options

Closes #70
Closes #71

Type of change

• Bug fix
• Feature
• Refactor (no behavior change)
• Documentation
• Performance improvement
• Tests
• Chore (dependencies, CI, tooling)

Checklist

• All tests pass (pnpm test)
• Files are formatted (pnpm format)
• I have added/updated tests for my changes (if applicable)
• I have added a changeset

AI-generated code disclosure

• This PR includes AI-generated code

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/clayterm@97

commit: e632001

[github-actions]

Size Increased — +1.4 KB

111.8 KB unpacked

[rauhryan]

[codspeed-hq]

Merging this PR will degrade performance by 99.83%

❌ 4 regressed benchmarks
✅ 19 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	UTF-8 3-byte character	87.6 µs	1,055,394.2 µs	-99.99%
❌	Simulation	SGR mouse press	68.7 µs	115,926.1 µs	-99.94%
❌	Simulation	Kitty protocol (CSI u with modifiers)	101 µs	82,934.5 µs	-99.88%
❌	Simulation	UTF-8 4-byte emoji	88.3 µs	702 µs	-87.43%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing flex-sizing-70-71 (e632001) with main (be7e746)}

[rauhryan]

Note:

this revealed two issues

1. how should we deal with box-sizing and what happens when the layout engine positions an element on top of the border of a box

2. it revealed a small gotcha on how clays command order and our cell rendering logic works for text and border glyphs