fix(routing): throw on unbalanced braces in route glob patterns

[Copilot]

Globs with unbalanced { / } passed to page.route() produced an invalid regex inside globToRegexPattern. The SyntaxError was raised lazily at request-match time, silently aborting matched requests and timing out navigations with ERR_ABORTED.

await page.route('http://*/foo{', route => route.continue());
await page.goto('http://localhost:1234/'); // hangs, then ERR_ABORTED

Changes

• packages/isomorphic/urlMatch.ts — globToRegexPattern now throws a descriptive error on unmatched {, unmatched }, and nested { instead of emitting an unterminated regex group.
• packages/playwright-core/src/client/network.ts — RouteHandler and WebSocketRouteHandler constructors eagerly call resolveGlobToRegexPattern for string globs, so invalid patterns surface at the page.route() / page.routeWebSocket() (and BrowserContext equivalents) call site rather than at request-match time.
• tests/page/interception.spec.ts — coverage for the new validation and for page.route() rejecting on an invalid glob.

Escaped braces (\\{, \\}) remain literal and unaffected.