Fix Playwright best practices and command correctness

[elaichenkov]

What changed

• Fixed invalid test.use placement in the mobile example.

• Replaced weak API assertion with await expect(response).toBeOK().

• Reworked the network-wait example to avoid race conditions (waitForResponse registered before click, stricter predicate).

• Replaced waitForNavigation() examples with waitForURL().

• Clarified role locator name matching:

  • exact match with { exact: true }
  • flexible regex match example

• Updated debugging docs:

  • removed misleading CLI usage
  • clarified slowMo usage in config

• Removed invalid CLI examples (e.g. project exclusion syntax, --headed=false).

• Fixed async rejection assertion example to:

  • await expect(asyncFn()).rejects.toThrow().