fix: address final-review findings (TopBar hydration, snapshot test, armor doc, inventory refresh test)

Fixes 4 Important findings from the final whole-branch review:
- /inventory never called WorldStore.load(), leaving the TopBar stuck on
  "loading" and characterLevel() silently defaulting to 1 for any character
  above level 1. Mirrors the same guard already used in HuntPageComponent.
- The combat/equipment snapshot-immutability integration test asserted only
  status/round, never the actual playerState snapshot the whole test claims
  to prove is untouched after a post-fight equip.
- Documented (comment only, no behavior change) that the demo character's
  armor dropping from the old hardcoded 6 to 0 is an intentional,
  spec-sanctioned tradeoff (Slice 0.5 spec Section19), not a bug.
- inventory.store.spec.ts's equip test used an identical inventory fixture
  before and after equip(), so a regression dropping the post-equip
  inventory re-fetch would still have passed. Now asserts the refetched
  fixture is actually reflected.

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

apps/web/src/app/features/inventory/inventory-page.component.ts

@@ -52,6 +52,9 @@ export class InventoryPageComponent implements OnInit {
   });
 
   ngOnInit(): void {
+    if (this.worldStore.character() === null) {
+      void this.worldStore.load();
+    }
     void this.inventoryStore.load();
   }