🧪 move tests into test directory, bump birdie to ignore non-gleam files

[JScearcy]

This is a an approach to testing a built lustre application.

• The vdom test will test the vdom script in isolation, without mounting a full app/runtime
• The counter test will build the 02-interactivity example and test the runtime via direct interaction with the + and - buttons, checking the rendered output.
• The bench test will run a simple benchmark on the smoke_test template (reused from vdom test)

[JScearcy]

Some feedback from Hayleigh:

1. Move config files to root, such as vitest config, package.json, etc
2. Configure snapshot location if possible to follow the same pattern as birdie - such as a vitest_snapshots directory
3. Test directories like test/counter_app_test/test/counter-app.test.js are maybe too verbose
4. Simplify the relative paths
5. Use lustre/dev build app for builds
6. Drop esbuild

[hayleigh-dot-dev]

Incredible stuff. This is going to be insanely valuable. I'm going to merge this and then maybe tweak some bits if I find time, thank you so much!