fix(ui): Draw focus rings on controls only, not on focusable containers (#66)

The global :focus-visible outline loads after the module CSS with the same
specificity, so every focusable container without its own override (the
Intentions list, other list/tree/menu popups) got a square blue frame. ee99b36
patched the Select popup only. Like IDEA, rings now mark controls (buttons,
links, fields, checkboxes, tabs…); lists, trees, tables and popups show focus
through their selected row, and the few rows that drew frames use the hover
background instead.

Claude-Session: https://claude.ai/code/session_01VUYsdXA2nkF5v6zsC93dpn

src/features/plugins/PluginsPage.module.css

@@ -155,8 +155,8 @@
   text-align: left;
 }
 .rowMain:focus-visible {
-  outline: 2px solid var(--accent);
-  outline-offset: -2px;
+  outline: none;
+  background: var(--bg-hover);
 }
 .rowName {
   overflow: hidden;