chore: unify code formatting and remove unused code

- Apply cargo fmt to Rust code with multiline error handling
- Apply Prettier formatting to TypeScript code with trailing commas
- Unify #[allow(non_snake_case)] attribute formatting
- Remove unused ProviderNotFound error variant from error.rs
- Add vitest-report.json to .gitignore to exclude test artifacts
- Optimize readability of error handling chains with vertical alignment

All tests passing: 22 Rust tests + 126 frontend tests

.gitignore

@@ -11,3 +11,4 @@ CLAUDE.md
 AGENTS.md
 /.claude
 /.vscode
+vitest-report.json