Add user dashboard to view and manage own claims

[artworxai]

Currently, there is no way for logged-in users to view a list of their own claims or manage them. The "Claim" menu item only opens the claim creation interface, but doesn't show existing claims created by the user.

Proposed Solution:
Add a "My Claims" menu item that appears when user is logged in, showing:

List of all claims created by the user
Validations received on each claim
Option to delete claims (if not yet endorsed)
Option to request endorsements from specific people

Additional Context:
Per discussion with @gvelez17: Claims should be immutable once endorsed to preserve trust, but users should be able to delete unendorsed claims.