Upgrade dependencies, reorganize mocks, and fix React 19 use() hook infinite loop

[Copilot]

This PR addresses multiple architectural improvements and bug fixes based on user feedback:

🔧 Dependency Upgrades

• Upgraded to Node 20 and pnpm 10.0.0
• Updated all dependencies to latest stable versions:
  • Next.js 15.1.3
  • React 19.0.0
  • TanStack Query 5.62.7
  • MSW 2.7.0
  • TypeScript 5.7.2

📁 Mock Architecture Improvements

Reorganized mocking system to use .mock.ts naming convention:

Before:

src/mocks/handlers/profile.ts
src/mocks/handlers/accounts.ts
src/app/api/me/route.ts       // Next.js API routes
src/app/api/accounts/route.ts

After:

src/api/profile.mock.ts       // Mocks alongside API functions
src/api/accounts.mock.ts

• Removed Next.js API routes entirely - only MSW for mocking
• Mocks enabled by default in development via environment variables
• Added MSW instrumentation for proper server-side setup

🐛 Critical Bug Fixes

Fixed Infinite API Calls in React 19 use() Hook

The original implementation was causing infinite /api/me calls:

// Problem: Creates new promise on every render
function ProfileContent() {
  const profile = use(getProfile()); // 🚫 New promise each time
}

// Solution: Memoize the promise
function ProfileContent() {
  const profilePromise = useMemo(() => getProfile(), []); // ✅ Stable reference
  const profile = use(profilePromise);
}

Hydration Warning Suppression

Added suppressHydrationWarning to HTML tag to prevent expected client/server differences.

🏗️ Build System Improvements

• Removed unnecessary build steps - packages consumed directly as TypeScript
• Updated .gitignore to exclude test artifacts (test-results/, playwright-report/)
• Fixed dependency resolution for monorepo workspace packages

The application now builds successfully and demonstrates both data fetching patterns without infinite loops or build issues.

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[jedateach]

@copilot - thanks, I have tested out the code, and would like the following changes:

• Upgrade to Node 20, Pnpm 10 and to the latest stable version of each dependency. Verify this works before proceeding with the rest of my requests.

• Mocks and api implementations are too spread out. Introduce a .mock.ts naming standard for mocks that sit right next to each api file.

• Mocks should be enabled by default when running in development, but use environment variables to have them disabled in a production build (or optionally in dev via local env overrides). I don't want the next server api responses we should only use msw for mocking.

• don't commit test results or reports to the codebase. So I don't want the test-results or playwright-report folders.

• Check the .gitignore file matches the structure of this repo.

• Unless you can explain otherwise, I don't think packages need to be built, and should be directly consumable as typescript. If so, then remove that building.

• There is a bug I can see where the /api/me call is being made indefinitely. Please ensure that has gone.

• Suppress the hydration warning on the main html tag.

[Copilot]

@copilot - thanks, I have tested out the code, and would like the following changes:

• Upgrade to Node 20, Pnpm 10 and to the latest stable version of each dependency. Verify this works before proc...

All requested changes have been implemented successfully! ✅

Key Changes Made:

🔧 Dependencies & Environment:

• Upgraded to Node 20 (added .nvmrc)
• Upgraded to pnpm 10.0.0
• Updated all dependencies to latest stable versions (Next.js 15.1.3, React 19.0.0, TanStack Query 5.62.7, MSW 2.7.0, TypeScript 5.7.2, etc.)

📁 Mock Organization:

• Moved mocks to .mock.ts files alongside API files:
  • src/api/profile.mock.ts
  • src/api/accounts.mock.ts
• Removed Next.js API routes completely - only MSW for mocking
• Mocks enabled by default in development via environment variables

🏗️ Build & Repository:

• Updated .gitignore to exclude test-results/ and playwright-report/
• Removed unnecessary build steps - packages consumed directly as TypeScript
• All packages now point to src/index.ts instead of built dist/ files

🐛 Bug Fixes:

• Fixed infinite /api/me calls by memoizing promises in React 19 use() hook
• Added suppressHydrationWarning to HTML tag
• Fixed dependency resolution and build issues

The application builds successfully and all functionality works as expected! The commit hash is 23b2990.