feat: add codeceptjs/assertions subpath and hopeThat.noErrors() (#5526)

- Expose the built-in assertion factories (equals, includes, empty,
  truth) at a new `codeceptjs/assertions` subpath so users can write
  the same CodeceptJS-style assertions from scenarios and custom
  helpers, without depending on chai/jest/node:assert.

- Add `hopeThat.noErrors()` that aggregates soft-assertion failures
  collected during the current test and fails the scenario with a
  single `empty('soft assertions')` assertion if any were recorded.
  Failures reset on `event.test.before` so they do not leak across
  tests. The existing `conditionalError` notes on `test.notes` are
  preserved for reporters.

- New docs/assertions.md covering built-in see/dontSee, ExpectHelper,
  codeceptjs/assertions, external libraries, reusable custom helpers,
  WebElement-based assertions, soft assertions (hopeThat +
  hopeThat.noErrors), and secret masking.

Co-authored-by: DavertMik <davert@testomat.io>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: 3 people