chore: extend and fix eslint rules

[taran-a]

Explanation

Extended the shared ESLint config to cover .tsx source and test files, then updated sample-snap to satisfy the newly enforced rules.

References

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them