perf(jsx): cache TypeScript Babel plugin config

[TheAlexLichter]

Summary

This PR caches Babel TypeScript plugin ConfigItems per Vue JSX plugin instance, avoiding repeated plugin initialization across TSX transforms.

Performance

Measured with Node 24.17.0 using 18 distinct module IDs, 3 warmup batches, and 20 measured batches per process.

Representative TSX input:

mode	before	after	change
production client	8.85 ms	6.25 ms	-29%
production SSR	7.36 ms	5.45 ms	-26%
serve client	7.51 ms	5.61 ms	-25%

18 copies of Nuxt's small TSX fixture:

mode	before	after	change
production client	3.81 ms	2.76 ms	-28%
production SSR	3.86 ms	2.77 ms	-28%
serve client	3.96 ms	2.88 ms	-27%

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/@vitejs/plugin-vue@799

npm i https://pkg.pr.new/@vitejs/plugin-vue-jsx@799

commit: 724f46b

[sapphi-red]

I've removed the tests as I thought it relied on the internals too much. I hope you don't mind.

[TheAlexLichter]

Not minding this at all! I also felt it was a bit too coupled but didn't find a better way