fix(gui-v2): breadcrumb navigation via router.push + button type + void logout

- FIX A (IMPORTANT): PrimeVue Breadcrumb ignores `route` key; map non-last
  items with `command: () => router.push(item.to)` for real client-side nav
- FIX B: add type="button" to all 6 native <button> chrome elements
- FIX C: authStore.logout() bare call matches project no-void pattern
- FIX D: document param-route edge case in toBreadcrumbItems
- FIX E: regression test asserts command+push on non-last, no command on last,
  no `route` key on any item

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

apps/app/src/composables/useBreadcrumb.ts

@@ -55,7 +55,11 @@ export function toBreadcrumbItems(matched: readonly BreadcrumbRouteRecord[]): Br
     if (isLast)
       return { label }
 
-    // Prefer path; fall back to name when path is absent/empty
+    // Prefer path; fall back to name when path is absent/empty.
+    // NOTE: a non-last record whose `path` is a param template (e.g. `/events/:id`)
+    // would yield an unresolved-template `to` — acceptable in foundation scope because
+    // param routes are normally the last (current, no-`to`) segment.
+    // TODO TECH-WS-GUI-REDESIGN: resolve param paths if a non-leaf param route ever needs a crumb link
     const to: RouteLocationRaw
       = record.path
         ? record.path