fix(admin): products canDeactivate guard, unblock npm, drop dead deps

RC-01 Phase 1 mechanical fixes (verified against current repo state,
not blindly reapplied from TODO.md):

- admin/products create/edit/duplicate now protected by an unsaved-
  changes guard (adminProductDirtyGuard), mirroring the existing
  categories pattern. AdminProductsFacade had zero dirty-tracking
  before this - added a dirty signal, set true on updateDraft(),
  cleared on load/create/successful save. Added confirmLeaveUnsaved
  to the adminProducts i18n section (en/ru/hy) - categories already
  had its own copy of this key, products didn't.
- barry-cache bumped ^0.1.0 -> ^0.9.3 (the pinned range no longer
  resolved on the registry - ETARGET - which had been silently
  blocking every npm install/uninstall all cycle).
- Removed primeng/primeicons (npm uninstall, now unblocked) - the
  only consumer (items-carousel) was already deleted in RC PERF-01.
- Removed core/search/services/search-history.service.ts, a dead
  1-line re-export with zero importers (verified: the real
  implementation is features/search/services/search-history.service.ts,
  used by search.facade.ts). Left core/search/models/* alone - those
  ARE live, imported by catalog components.

Verified before touching: HeaderConfig.showProfile toggle is already
removed from the header-section editor template (TODO.md was stale on
this one) - no change needed, will correct the tracking doc separately.

tsc --noEmit clean, npm run build green (bundle unchanged, primeng
was already tree-shaken out, this just removes the dead dependency
declaration itself).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/i18n/en.ts

@@ -1543,6 +1543,7 @@ export const en: Translations = {
     recommendNone: 'Nice work — your category structure is in good shape.',
   },
   adminProducts: {
+    confirmLeaveUnsaved: 'You have unsaved changes. Leave without saving?',
     emptyTitle: 'No products found',
     emptyDescription: 'Try adjusting your filters, or create a new product.',
     emptyGuide: 'Good products have a clear title, at least one photo, a price, and a short description — that\'s enough to publish. You can always add more detail later.',