chore(repo): test migration to vitest. phase 1

[charliecreates]

Summary

Migrates all Phase 1 packages in #1974 from Ava to Vitest:

• packages/beep
• packages/buble
• packages/data-uri
• packages/dsv
• packages/eslint
• packages/graphql
• packages/image
• packages/inject
• packages/legacy
• packages/multi-entry
• packages/strip
• packages/sucrase
• packages/swc
• packages/virtual
• packages/yaml

Key updates:

• Standardizes per-package scripts to:
  • test: vitest --config ../../.config/vitest.config.mts run
  • ci:test: pnpm test -- --reporter=verbose (plus existing test:ts where applicable)
• Converts Ava APIs/assertions to Vitest equivalents in tests.
• Updates shared Vitest config for Phase 1 migration needs (CJS/global test compatibility, test/test.* discovery, snapshot path parity in test/snapshots).
• Migrates assertion fixtures relying on injected assertions (data-uri, dsv, legacy, sucrase, yaml).
• Regenerates snapshot .snap files in Vitest format and removes Ava .md snapshot reports for migrated packages.

Validation

# package tests (snapshot update where needed)
for p in beep buble data-uri dsv eslint graphql image inject legacy multi-entry strip sucrase swc virtual yaml; do
  (cd packages/$p && pnpm test -- -u)
done

# type tests where present
for p in buble data-uri eslint graphql inject sucrase swc virtual; do
  (cd packages/$p && pnpm test:ts)
done

Notes

• Adds an explicit timeout for packages/eslint/test/test.mjs (works with flat config) to avoid Vitest default-timeout flakiness.

Refs #1974

[shellscape]

@CharlieHelps please fix failing CI issues. Your task is complete when all checks are green.

[charliecreates]

Done — I fixed the CI failures on this PR, and all checks are now green (5/5) on 8e90d0a.

Pushed fixes:

• 559affc
• fee2b18
• 8e90d0a