fix(router): clear the matched route between requests

[osbre]

Implement RouterReset to unregister MatchedRoute from the container during resets, and clear the binding in MatchRouteMiddleware before matching.

Problem

MatchRouteMiddleware binds MatchedRoute into the container as a singleton. In long-running workers (FrankenPHP worker mode) or test suites where the container is reused across requests, this state leaks across boundaries: GenericContainer::reset() clears resolved singletons and dynamic initializers, but not singletonDefinitions, where the binding lives. Anything sharing the container - the next request, a console command, a deferred task - incorrectly inherits the previous request's matched route, causing stale data in URI generation, route model binding, and middleware execution.

Solution

• Create RouterReset implementing Resettable to automatically unregister MatchedRoute::class during container resets, discovered via ResettableDiscovery and following the existing resets from worker mode support (feat(core)!: worker mode support #2172).
• Clear any existing MatchedRoute binding inside MatchRouteMiddleware before running a new match, ensuring safe reuse even when container resets do not occur, ie in test suite:

$this->http->get('/docs/installation')->assertOk();
$this->http->get('/does-not-exist')->assertNotFound();

is_current_uri([DocsController::class, 'show'], slug: 'installation'); // true, on a 404

[github-actions]

Benchmark Results

Comparison of fix/matched-route-staleness against 3.x (cf035264805564eb789f2741734e481aa3696b4d).

Open to see the benchmark results

Benchmark	Set	Mem. Peak	Time	Variability
ViewRenderBench(benchPlainHtml)	-	22.035mb 0.00%	489.072μs -7.30%	±2.09% +127.14%

_{Generated by phpbench against commit c31738d}

[aidan-casey]

Nice! Looks good to me.