fix(valid-expect): handle static expect APIs

[w3lld1]

Summary

• classify expect.soft, expect.poll, and expect.element as expect APIs instead of matchers
• validate their actual matcher chains and argument counts through the existing valid-expect logic
• add coverage for valid chains, missing matchers, modifiers, and argument-count diagnostics

Validation

• corepack pnpm test --run — 82 files, 2,357 tests passed
• corepack pnpm typecheck
• corepack pnpm lint:js
• corepack pnpm format
• corepack pnpm build

Local validation used Node.js 20.20.0; the repository CI matrix will additionally exercise Node.js 22 and 24 on Ubuntu and Windows.

Fixes #921
Fixes #922

[veritem]

thanks