feat: Pomerium assertion headers used in UI now to display user info

[nickytonline]

• Added UserContext using @pomerium/js-sdk to extract Pomerium assertion headers.
• Updated Chat component to greet user by name, similar to Claude.
• Enhanced Header to show user's email and profile picture.
• Wrapped app in UserProvider for global access to user identity.
• Added @pomerium/js-sdk to package.json and lockfile.

For the avatar URL, I was looking at the Enterprise Console source code and we handle it differently @wasaga and we seem to extend the UserInfo with some getters/setters. We can chat tomorrow when you're in SF.

Closes #41

[Copilot]

Pull Request Overview

Adds Pomerium-based user identity to the UI and personalizes components accordingly

• Introduces UserContext to fetch and provide user info via @pomerium/js-sdk
• Wraps the app in UserProvider and updates Header and Chat to display name, email, and avatar
• Adds @pomerium/js-sdk dependency

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/routes/__root.tsx	Wrapped <ModelProvider> in <UserProvider>
src/contexts/UserContext.tsx	New context to fetch and expose Pomerium user info
src/components/Header.tsx	Displays user’s email, name, and profile picture in the header
src/components/Chat.tsx	Personalizes initial chat greeting with the user’s first name
package.json	Added @pomerium/js-sdk dependency

Comments suppressed due to low confidence (2)

src/contexts/UserContext.tsx:36

• [nitpick] Using a generic ['user'] key can collide with other queries. Rename to ['userInfo'] or similar to make it more specific.

queryKey: ['user'],

src/contexts/UserContext.tsx:20

• Core logic in fetchUserInfo and UserProvider lacks unit tests. Add tests to verify fallback behavior and error handling of getBrowserUser.

async function fetchUserInfo(): Promise<UserInfo> {