feat(helpers): add seeInClipboard, seeClipboardEquals and clearClipboard

[DavertMik]

Adds seeInClipboard(), seeClipboardEquals() and clearClipboard() to every browser helper.

I.click('Copy to clipboard')
I.seeInClipboard('https://codecept.io')
I.seeClipboardEquals('https://codecept.io')
I.clearClipboard()

How each helper reads the clipboard

Helper	Mechanism
Playwright	page.context().grantPermissions(['clipboard-read', 'clipboard-write']) + page.evaluate
Puppeteer	browserContext().overridePermissions(origin, [...]) — clipboard-sanitized-write is required too, or writeText stays denied
WebDriver	browser.setPermissions({ name: 'clipboard-read' }, 'granted') + executeAsync, since execute does not await promises under W3C
CDPBrowser (inherited by Obscura, Kitesurf)	raw Browser.grantPermissions with the CDP permission names clipboardReadWrite / clipboardSanitizedWrite
Appium	native getClipboard / setClipboard device commands (base64), falling back to the WebDriver implementation on a non-mobile session

Two details worth calling out:

• Permission is granted per call rather than at browser start, because session() and restart recreate the context.
• The page is brought to front first — Chromium rejects readText() with "Document is not focused" when another tab holds focus, and the acceptance suite opens tabs.
• The in-page read races against a 5s timeout, so a browser that neither grants nor denies access (a paste prompt that never appears in a headless run) fails the step instead of hanging it.

Tests

test/helper/webapi.js covers all helpers through the new /form/clipboard fixture, which uses a real copy button rather than writing the clipboard from the test, so the read path is genuinely exercised.

Obscura is skipped with a verified reason: its navigator.clipboard.writeText() resolves but stores nothing, so readText() always returns ''.

Verification

Check	Result
npm run test:unit	832 passed, 0 failed
npm run test:runner	279 passed, 0 failed
definitions_test.js (def gate)	12 passing
Playwright / Puppeteer / CDPBrowser clipboard specs	9/9 passing
WebDriver against chromedriver directly	read, write, clear and the negative assertion all pass
Playwright acceptance suite	64 passed, no hangs; the one failure is the pre-existing mock server test
eslint	clean

npm run dtslint reports 2 errors about conflicting *Config identifiers — confirmed pre-existing by regenerating typings from a clean tree.

Not verified locally: WebDriver through Selenium Grid, Appium (no device), and Kitesurf. If Cloudflare's remote browser refuses Browser.grantPermissions, that suite will need an Obscura-style skip; no CI workflow runs it today.

docs/helpers/*.md is intentionally not included — the doc-generation workflow regenerates and commits it on push to 4.x.

🤖 Generated with Claude Code