feat(chat): animated welcome screen for new users

[Nacho1499]

Closes #149

What does this PR do:
This PR introduces an interactive, fully responsive, and animated welcome/onboarding screen for new users on the chat dashboard when no conversation or group is currently selected. Additionally, it hardens the frontend's resilience against missing configuration fields, ensuring the UI mounts seamlessly in mock or fallback local development environments.

Why is this change necessary? Prior to this change, users without active or selected chats were greeted by an empty chat pane, which disrupted onboarding flow. Furthermore, developers working without local microservices or live database links actively faced rigid runtime error overlays due to strict network assertion handlers.

Feature implemented:
[x] Added an animated onboarding dashboard screen.ChatWelcomeState
[x] Implemented prominent call-to-action buttons for "Create Group" and "Join Group" matching mobile and desktop breakpoints.

Testing & Validation:
[x] Tested locally
[x] No runtime errors
[x] Existing features work as expected
[x] Edge cases handled

Breaking Changes:
[x] No breaking changes

Contributor Checklist (MANDATORY)
[x] I was assigned to this issue
[x] My code follows the project structure and conventions
[x] I have tested my changes thoroughly
[x] I did not introduce unnecessary dependencies
[x] I have linked the issue (Closes #149)
[x] This PR is ready for review

Notes for Reviewer:
Key areas to review:
[x] Look over the defensive try/catch architecture added to and the connection listeners to ensure strict environment safety patterns are maintained.src/app/chat/page.tsxWebSocketClient.
-Verify layout, responsiveness, and animation rendering of the newly appended welcome panel components on narrow viewports.

Known limitations:
[x]While operating in local preview mode under standard dummy variables (), real-time sync hooks () will cleanly log safety warnings in the terminal instead of connecting, which is the expected behavior until live infrastructure keys are provided.dummy.supabase.couseWebSocket

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[Nacho1499]