chore(social-client): drop redundant comment, harden defineProperty

Per code-review:
- Drop the inline comment in sendFriendRequest; the commit message
  for the prior commit already covers the why and CLAUDE.md prefers
  no comments when the code is self-explanatory.
- Add writable: true to the window.location defineProperty in the
  test so re-firing beforeEach across jsdom version drift is safe.

packages/web/src/stores/socialStore.sendRequest.test.ts

@@ -51,6 +51,7 @@ describe('socialStore.sendFriendRequest — case-insensitive domain routing', ()
     // Override it for routing tests.
     Object.defineProperty(window, 'location', {
       configurable: true,
+      writable: true,
       value: { ...window.location, host: 'local.test', hostname: 'local.test' },
     });
   });