chore: improve invitation flow, update project dependencies and documentation for Next.js 16 (#408)

* chore: update project dependencies and documentation for Next.js 16

- Upgraded Next.js from version 15 to 16 across various documentation files and components.
- Updated references to Next.js 16 in AGENTS.md and CLAUDE.md for consistency.
- Incremented application version to 2.21.0 in package.json.
- Refactored identity setup components to improve user experience and added confirmation dialogs for authentication methods.
- Enhanced invitation flow with new logic for handling user redirection and token generation.

* refactor: streamline invitation flow in e2e tests

- Simplified the invitation flow test by using a predefined email instead of generating a random one.
- Removed unnecessary steps such as clearing cookies and reloading the page before user sign-up.
- Enhanced clarity by eliminating commented-out code related to identity verification and user membership checks.

* refactor: improve code readability in IdentitiesPage and UpdatePasswordForm components

- Enhanced formatting of JSX elements in IdentitiesPage and UpdatePasswordForm for better readability.
- Adjusted indentation and line breaks to maintain consistent coding style across components.

* refactor: enhance LinkAccountsList component with user redirection logic

- Updated the LinkAccountsList component to include a redirectToPath option in the useLinkIdentityWithProvider hook for improved user experience.
- Removed redundant user hook declaration to streamline the code structure.

* refactor: update account setup logic in JoinTeamAccountPage

- Introduced a check for email-only authentication support to streamline account setup requirements.
- Adjusted the conditions for determining if a new account should set up additional authentication methods, enhancing user experience for new users.

apps/web/CLAUDE.md

@@ -40,7 +40,7 @@ The `[account]` parameter is the `accounts.slug` property, not the ID
 
 ## React Server Components - Async Pattern
 
-**CRITICAL**: In Next.js 15, always await params directly in async server components:
+**CRITICAL**: In Next.js 16, always await params directly in async server components:
 
 ```typescript
 // ❌ WRONG - Don't use React.use() in async functions
@@ -48,12 +48,12 @@ async function Page({ params }: Props) {
   const { account } = use(params);
 }
 
-// ✅ CORRECT - await params directly in Next.js 15
+// ✅ CORRECT - await params directly in Next.js 16
 async function Page({ params }: Props) {
   const { account } = await params; // ✅ Server component pattern
 }
 
-// ✅ CORRECT - "use" in non-async functions in Next.js 15
+// ✅ CORRECT - "use" in non-async functions in Next.js 16
 function Page({ params }: Props) {
   const { account } = use(params); // ✅ Server component pattern
 }