chore(fix): linting and formatting project files

Title

chore: set up eslint/prettier and format the codebase

Description

This MR standardizes linting and formatting across the project and brings the current codebase into compliance with the configured checks.

What Changed

• Added ESLint and Prettier dependencies
• Added lint, format, and format:check scripts
• Added a Prettier configuration and ignore rules
• Updated the ESLint configuration to lint source, tests, and config files
• Excluded generated/artifact paths such as builds/, cache/, and coverage/
• Excluded generated Vite outputs from lint/format scope
• Applied Prettier formatting across the codebase
• Fixed one React hooks cleanup warning

Why

• The repo had an ESLint config but was missing the required packages and scripts
• Formatting was inconsistent across source, tests, and config files
• Generated files were being picked up by linting and obscuring real issues

Validation

• npm run format:check
• npm run lint
• npx tsc --noEmit
• npx vitest run

Notes

• builds/ and cache/ are local/generated artifacts and are not part of this MR
• Generated Vite outputs are excluded from lint/format scope in favor of the source TypeScript config