feat: add Grimmory/Booklore push integration

- Added "Push to Library" button to issues archive
- Implemented direct API upload to Grimmory/Booklore
- Added support for `.env` files via `python-dotenv`
- Handled 409 Conflict for duplicate files gracefully
- Resolved library name to numeric ID for direct uploads
- Fixed SQLAlchemy and ebooklib warnings in tests
- Added comprehensive tests for push functionality

Made-with: Cursor

templates/issues.html

@@ -29,6 +29,11 @@
             <td class="issue-actions">
                 <a href="/issues/{{ item.issue.id }}/read" role="button" class="outline">Read</a>
                 <a href="/issues/{{ item.issue.id }}/download" role="button" class="outline">Download</a>
+                {% if config.GRIMMORY_URL and config.GRIMMORY_USERNAME and config.GRIMMORY_PASSWORD %}
+                <form method="post" action="/issues/{{ item.issue.id }}/push">
+                    <button type="submit" class="outline">Push to Library</button>
+                </form>
+                {% endif %}
                 <form method="post" action="/issues/{{ item.issue.id }}/regenerate">
                     <button type="submit" class="outline contrast">Regenerate</button>
                 </form>