feat(11-02): UIE-01 edit modal — Edit button per row, Pico dialog, E2E tests

- Create printer_edit_modal.html: native dialog with HTMX PATCH form, Alpine.js portEdited=true
- Update printer_list.html Actions td: include edit modal partial before Delete button
- Create tests/e2e/test_printer_edit.py: modal open/pre-fill and submit/list-update E2E tests
- Fix E2E row targeting to use locator(tr, has=a:has-text) for session-scoped server safety

imptune/templates/partials/printer_list.html

@@ -31,6 +31,7 @@
           <td>{{ p.paper_size }}</td>
           <td>{{ 'Yes' if p.collate else 'No' }}</td>
           <td>
+            {% include "partials/printer_edit_modal.html" %}
             <button
               hx-delete="/printers/{{ p.id }}"
               hx-target="#printer-list"