tooling: add size-limit and size-limit-action to measure sizes of individual exports/examples

[EskiMojo14]

size-limit-action checks out the version from main and compares against the version from the given PR, giving a report of how the size of each export has changed.

This uses my fork https://github.com/eskimojo14/size-limit-action, which adds a "size-margin" option to filter out exports that didn't change from the Github report (as including unchanged exports would be very noisy).

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Project	Deployment	Preview	Comments	Updated (UTC)
valibot	Ready	Preview	Comment	Sep 23, 2025 4:46pm

[fabian-hiller]

Hey 👋 thank you! Is this PR in a final stage?

[EskiMojo14]

Hey 👋 thank you! Is this PR in a final stage?

yep, should be