Feature: Space creation flow from UI stub to real create

[mjkatgithub]

Goal

Replace the current create-space UI stub with a complete space creation flow.

Scope

• Implement real space creation through Matrix API calls
• Provide validation and clear user feedback for create outcomes
• Refresh navigation state to include the newly created space

Branch

feature/space-creation-flow

Acceptance Criteria

• Users can create a new space from the app UI
• Success and error states are clearly communicated
• Newly created spaces appear in navigation without manual refresh

Test Checklist

Unit

• Create payload mapping and validation logic
• Error handling and fallback messages

Integration

• Create flow updates stores and navigation state
• Form validation prevents invalid submissions

E2E

• Create a space and verify it appears in the rail
• Verify error feedback for invalid or failed create attempts

Notes

• Keep API and UI contracts compatible with later space settings support.