Update functions template to meet modern dev practices.

[taeold]

• Removed the ESLint-on-init prompt; JavaScript and TypeScript setups now always scaffold a Biome config and skip adding lint steps for JS predeploys
• Refreshed both JS/TS function templates to use ESM syntax
• Consolidated template packages: renamed the “nolint” variants to the primary package.json, added type: "module"
• Bumped firebase- admin/firebase-functions to current versions.
• Modernized the TypeScript tsconfig.json (ES2022 target, ESNext modules, bundler resolution, skip lib checks)

[gemini-code-assist]

Summary of Changes

Hello @taeold, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly updates the Firebase Functions templates to align with modern JavaScript and TypeScript development standards. It transitions from ESLint to Biome for linting, adopts ESM for module management, updates Firebase SDK dependencies, and refines TypeScript compiler options. The changes streamline the initialization process by removing the ESLint prompt and consolidating template files.

Highlights

• Intent: This pull request aims to modernize the Firebase Functions templates by updating them to current development practices. Key changes include adopting ECMAScript Modules (ESM), replacing ESLint with Biome for linting, updating core dependencies, and modernizing TypeScript configurations.
• Key Changes: 1. Linting Tooling: ESLint has been replaced by Biome as the default linter for both JavaScript and TypeScript function templates. The interactive prompt to enable ESLint during initialization has been removed, and Biome configuration files (biome.json) are now scaffolded by default. Consequently, .eslintrc.js and tsconfig.dev.json files have been removed from templates. 2. Module System: Both JavaScript and TypeScript function templates have been updated to use ECMAScript Modules (ESM) syntax (import/export), reflected by the addition of "type": "module" in package.json. 3. Dependency Updates: The firebase-admin and firebase-functions packages have been bumped to their latest versions (^13.5.0 and ^6.4.0 respectively). 4. TypeScript Configuration: The tsconfig.json for TypeScript projects has been modernized with target: ES2022, module: ESNext, moduleResolution: Bundler, verbatimModuleSyntax: true, and skipLibCheck: true. 5. Template Consolidation: Separate package.json templates for 'lint' and 'nolint' variants have been consolidated into a single package.json file for both JS and TS. 6. Predeploy Scripts: The predeploy scripts have been adjusted; JavaScript templates no longer include a lint step, while TypeScript templates now include npm run lint (using Biome) and npm run build.
• Reviewer Activity: No specific reviewer activity was provided in the context.

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[gemini-code-assist]

Code Review

This pull request does a great job of modernizing the Firebase Functions templates by introducing Biome, adopting ESM syntax, and updating dependencies. The code is cleaner and the setup process is simpler. I've found one high-severity issue where the implementation and tests for TypeScript predeploy hooks are inconsistent. Please see my detailed comment below.