The cdp_processor decided whether to take the spawn-and-defer navigation path
with `text.contains("Page.navigate")`, which also matches
`Page.navigateToHistoryEntry`. goBack / goForward (both Puppeteer and
Playwright drive Page.navigateToHistoryEntry) were misrouted into the raw
navigate path, which reads an absent `url` param and fails with
"Invalid URL: relative URL without a base", so history navigation never
reached its real handler. Any frame merely embedding the literal
"Page.navigate" (e.g. a Runtime.evaluate expression) was misrouted the same
way.
Match on the parsed CDP method instead, so only an exact Page.navigate takes
the navigation path.
Fixes#363.