fix(web-integration): align yaml waitForNetworkIdle behavior and docs

[EAGzzyCSL]

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[EAGzzyCSL]

beta：https://github.com/web-infra-dev/midscene/actions/runs/23937425983

[JiwaniZakir]

The new test in agent-launcher.test.ts verifies the plumbing by inspecting the internal property (agent.page as any).waitForNetworkIdleTimeout, which is testing implementation state rather than observable behavior — the base-page-invoke-action.test.ts test is the more meaningful one here since it actually asserts waitForNetworkIdle is called with the right timeout argument. More importantly, neither the new agent-launcher test nor any other test in this diff covers the continueOnNetworkIdleError: false code path during the initial goto — the docs now explicitly call out that this setting causes a hard failure on timeout during URL load, but that behavior appears entirely untested. In agent-launcher.ts, the guard typeof target.waitForNetworkIdle?.timeout === 'number' correctly avoids passing stringified values, but a timeout: 0 would silently be forwarded and could cause every action-time idle wait to immediately error out, which may be worth clamping or documenting.