feat: add responsive snapshot capture, cookie capture, and cross-origin iframe support

[bhokaremoin]

Summary

This PR introduces three new snapshot capture features to the Percy Playwright Java SDK:

1. Responsive Snapshot Capture — Automatically captures DOM snapshots at multiple viewport widths in a single snapshot() call.
2. Cookie Capture — Attaches all page cookies to every snapshot payload so the CLI can use them during asset discovery.
3. Cross-Origin (CORS) Iframe Capture — Detects cross-origin iframes on the page, serializes their DOM independently, and stitches them into the snapshot via data-percy-element-id.

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Feature Details

1. Responsive Snapshot Capture

• snapshot() now checks isCaptureResponsiveDOM() to decide between a single capture and a multi-width responsive capture.
• Responsive capture is enabled via:
  • SDK option: options.put("responsiveSnapshotCapture", true)
  • CLI config: snapshot.responsiveSnapshotCapture: true
  • Disabled when percy.deferUploads: true (not compatible with deferred uploads)
• Viewport widths/heights are fetched from the new Percy CLI endpoint GET /percy/widths-config.
• For each width: resizes viewport → waits for window.resizeCount (via PercyDOM.waitForResize()) → optionally reloads → optionally sleeps → captures DOM.
• Original viewport is restored after all widths are captured.

New environment variables:

Variable	Description
RESPONSIVE_CAPTURE_SLEEP_TIME	Sleep in seconds between each width capture
PERCY_RESPONSIVE_CAPTURE_RELOAD_PAGE	Reload page between captures (true/false)
PERCY_RESPONSIVE_CAPTURE_MIN_HEIGHT	Adjust height for browser chrome via outerHeight - innerHeight + minH

2. Cookie Capture

• Before each DOM serialization, page.context().cookies() is collected (with graceful fallback on failure).
• Cookies are serialized as plain maps (name, value, domain, path, expires, httpOnly, secure, sameSite) and attached as cookies in the snapshot payload.

3. Cross-Origin (CORS) Iframe Capture

• getSerializedDOM() filters page.frames() to find frames whose host differs from the main page host.
• For each cross-origin frame: injects the Percy DOM script → calls PercyDOM.serialize({enableJavaScript: true}) → retrieves the matching data-percy-element-id from the main page DOM.
• Processed frames are attached as corsIframes in the snapshot payload.
• A new test fixture cors-iframe.html embeds https://todomvc.com/examples/react/dist/ to provide a real cross-origin frame for integration testing.

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Other Changes

• HTTP timeout: request() now uses a 600-second socket/connect timeout (was none), preventing long snapshot posts from hanging indefinitely.
• CLI config caching: The healthcheck response now stores the CLI's config object, used to drive responsive capture and deferUploads behavior without restarting.
• Structured logging: log() now POSTs {message, level} JSON to the Percy CLI /percy/log endpoint in addition to printing to stdout. Debug-level messages are suppressed from stdout unless PERCY_LOGLEVEL=debug.
• Percy CLI: Bumped @percy/cli to ^1.31.10-alpha.0 to pick up the widths-config and /percy/log endpoints.

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Tests

• Unit tests for isCaptureResponsiveDOM — SDK option, CLI config, and deferUploads override.
• Unit tests for cookie serialization — populated and empty cookie list.
• Unit tests for CORS iframe detection — cross-origin frame captured, same-origin frame skipped.
• Integration tests for responsive snapshot capture and CORS iframe snapshot.

[Copilot]

Pull request overview

Adds new snapshot-capture capabilities to the Percy Playwright Java SDK (responsive multi-viewport capture, cookie attachment, and cross-origin iframe stitching) along with CLI-driven configuration and improved logging/timeout behavior.

Changes:

• Implement responsive snapshot capture driven by CLI /percy/widths-config, with viewport resizing/reload/sleep support.
• Attach cookies and captured cross-origin iframe snapshots into the DOM snapshot payload.
• Add structured CLI logging, request timeouts, and tests/fixtures for the new behaviors.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 8 comments.

File	Description
src/main/java/io/percy/playwright/Percy.java	Core implementation for responsive capture, cookie capture, CORS iframe capture, CLI config caching, structured logging, and HTTP timeouts
src/test/java/io/percy/playwright/SDKTest.java	Adds unit/integration tests for responsive capture, cookies, and CORS iframes
src/test/resources/testapp/cors-iframe.html	New fixture page embedding a cross-origin iframe
package.json	Updates Percy CLI devDependency to an alpha version range

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[Copilot]

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[Copilot]

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[Copilot]

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