fix: rename "Final Version" to "Sent" on contract documents

The generated PDF/DOCX are what was sent to the sponsor, not the
final executed version. "Sent" is accurate, "Final Version" was
misleading for contracts still awaiting signature.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: JacobCoffee

apps/sponsors/templates/sponsors/manage/sponsorship_detail.html

@@ -331,12 +331,12 @@ <h2>Contract</h2>
             <!-- Stored sent documents -->
             {% if contract.document %}
             <a href="{{ contract.document.url }}" target="_blank" style="display:inline-flex;align-items:center;gap:6px;padding:6px 12px;background:#fff8dc;border:1px solid #ffd43b;border-radius:4px;font-size:12px;color:#333;text-decoration:none;">
-                <span style="color:#e74c3c;font-weight:700;">PDF</span> Final Version
+                <span style="color:#e74c3c;font-weight:700;">PDF</span> Sent
             </a>
             {% endif %}
             {% if contract.document_docx %}
             <a href="{{ contract.document_docx.url }}" target="_blank" style="display:inline-flex;align-items:center;gap:6px;padding:6px 12px;background:#fff8dc;border:1px solid #ffd43b;border-radius:4px;font-size:12px;color:#333;text-decoration:none;">
-                <span style="color:#3776ab;font-weight:700;">DOCX</span> Final Version
+                <span style="color:#3776ab;font-weight:700;">DOCX</span> Sent
             </a>
             {% endif %}
             <!-- Signed document -->