[codex] make profile card share button real

[saurabhhhcodes]

Closes #32

Summary

• replace the fake profile card toast with a real clipboard copy action for the public profile card URL
• move the profile card modal off hardcoded dark-only surfaces onto theme variables so light mode renders correctly
• add focused template/style assertions to keep the share flow and theme-safe surfaces from regressing

Validation

• ........... [100%]
  11 passed in 0.13s

[vercel]

Someone is attempting to deploy a commit to the mohitkumhar's projects Team on Vercel.

A member of the Team first needs to authorize it.