Setup wizard: plugin display names + GE-Enforce next-steps pointer

Plugins list now carries a displayname (manifest display_name, else the
machine name title-cased). Adds display_name to the four whose title-case
was wrong: GE-Enforce, USB, Measuring Tools, Knowledge Base. The setup
wizard Features step and Settings > Plugins render it, so "Geenforce"/"Usb"
are gone.

Finish step shows a pointer when GE-Enforce is enabled: it still needs a
scoped service token (Settings > API Tokens) and a share export root
(GE-Enforce page) before the fleet uses it - operational config the wizard
does not collect.

frontend build green; naming green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

shopdb/plugins/__init__.py

@@ -155,6 +155,11 @@ class PluginManager:
                     manifest = self.loader.load_manifest(name)
                     available.append({
                         'name': meta.name,
+                        # Human label for UIs. Manifest display_name wins; else
+                        # title-case the machine name (right for most, e.g.
+                        # "computers" -> "Computers").
+                        'displayname': (manifest.get('display_name')
+                                        or meta.name.replace('_', ' ').title()),
                         'version': meta.version,
                         'description': meta.description,
                         'author': meta.author,