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/api/src/combat/combat-equipment-integration.spec.ts

@@ -367,6 +367,10 @@ describe('equipping Räuberklinge increases combat damage (spec §45, §60)', ()
 
     await equipmentService.equip(CHARACTER_ID, BANDIT_BLADE_ITEM_ID);
 
+    // The finished combat's playerState snapshot (written once at startCombat)
+    // must not be retroactively rewritten by equipping after the fight ends.
+    expect(state.combats[0].playerState).toEqual({ attack: 6, weaponDamage: 8, armor: 0 });
+
     const reloaded = await combatService.getCombat(CHARACTER_ID, combat.id);
     expect(reloaded.status).toBe(result.status);
     expect(reloaded.round).toBe(result.round);