Add GitHub source code link to sidebar navigation

Add "View Source Code" link at bottom of sidebar pointing to repository.
Styled subtly with tertiary text color and dotted underline.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

kjvstudy_org/templates/base.html

@@ -977,6 +977,13 @@
             </ul>
         </div>
 
+        <!-- Source Code -->
+        <div style="margin-top: 2rem; padding-top: 1rem; border-top: 1px solid var(--border-color);">
+            <p style="font-size: 0.85rem; color: var(--text-tertiary); text-align: center;">
+                <a href="https://github.com/kennethreitz/kjvstudy.org" target="_blank" rel="noopener" style="color: var(--text-tertiary); text-decoration: none; border-bottom: 1px dotted var(--border-color-dark);">View Source Code</a>
+            </p>
+        </div>
+
         <!-- Flourish -->
         <div class="sidebar-flourish">⁂</div>
     </nav>