bug: invite referral copy button fails when clipboard API is blocked

[absalonCRC]

Summary

The Invite Friends dashboard copy button calls navigator.clipboard.writeText directly. In insecure contexts, embedded browsers, denied permissions, or browser privacy modes where the Clipboard API is missing or rejects writes, clicking Copy throws and the user gets no useful fallback.

Steps to reproduce

1. Open /dashboard/referrals in a context where Clipboard API writes are unavailable or denied.
2. Click the Copy button beside the referral link.

Expected

The page should still attempt a DOM copy fallback or show a clear manual-copy message.

Actual

The direct navigator.clipboard.writeText call can reject/throw and the Invite Friends copy flow fails.

Proposed fix

Wrap Clipboard API usage, fall back to a temporary textarea + document.execCommand("copy"), and show a manual-copy error if both paths fail.

[morganschp]

Covered by the updated PR #214: #214

The new commit wraps the Invite Friends copy action with a Clipboard API fallback to a temporary textarea and shows a manual-copy error if both paths fail. It also adds component regression coverage for blocked Clipboard API writes and total copy failure.