Add one-shot capture APIs to Java

[vincebln2]

Fixes #367.

Java exposed persistent event listeners but none of the one-shot capture surface available in JavaScript and Python. Callers had to build their own listener, ordering, timeout, and cleanup around every action.

What changed

• Added page.capture() with typed request, response, navigation, download, dialog, and generic event capture methods
• Every method installs its listener before starting the action and removes exactly that listener on success, timeout, interruption, or action failure
• Capture actions run on a daemon executor. The event can return while an action is blocked by a native dialog, so Java does not inherit the capture.dialog deadlock tracked in capture.dialog(fn) deadlocks when fn calls page.evaluate("alert(...)") (Python Client) #146
• Added Java navigation event delivery for load, fragment, and history updates

Verified:

• Focused CaptureTest: 7/7 green on Chrome
• Tests cover all capture families, the blocking alert reproduction, generic console capture, action failure, timeout, and reuse after cleanup
• validateCapabilityMarkers and compileTestJava green
• Fork CI covers the complete Chrome and Firefox suites