Mem-Client: No Arbitrary Playwright Waits

Playwright tests must avoid fixed-time synchronization waits.

Rationale:
- Fixed sleeps create flaky and slow tests.

Scope:
- PR review policy for `domains/frontend/mem-client/e2e/**` tests and related e2e helper utilities.

Trigger:
- A PR adds or changes synchronization waits in scope.

Approval checks:
1) No new fixed-time waits are introduced (`page.waitForTimeout(...)`, `setTimeout`-based sleeps, or equivalent sync sleeps).
2) Wait logic uses condition-based Playwright primitives (locator/network/assertion/navigation conditions).

Evidence:
- Diff shows condition-based waits and no fixed-time synchronization additions.

Decision:
- Return NOT APPROVED when trigger is met and fixed-time wait synchronization is introduced.