[6.x] Refactor site route fallback

[riasvdv]

Description

Refactors site request fallback handling around a single Laravel fallback route, keeps project and plugin routes compatible with route caching, removes recursive HTTP-kernel entry for previews and legacy routes, and moves final Yii URL-rule compatibility into adapter middleware.

Consolidates adjacent request middleware now that routing runs through the simplified pipeline.

The most important change here is that it removes re-entering the HTTP kernel, causing the whole middleware and HTTP stack to be ran again

BEFORE

Request
  │
  ▼
Laravel routes
  │
  ▼
Element middleware
  ├─ template ──────────> Response
  ├─ controller ────────> Response
  └─ action ────────────> Re-enter kernel
                              │
                              ▼
                         Yii fallback
                              │ 404
                              ▼
                       Public template
                              │
                              ▼
                         Response / 404


AFTER

Request
  │
  ▼
Laravel routes
  ├─ fixed core/plugin
  ├─ project-config
  └─ site fallback
          │
          ▼
       Element
          │ 404
          ▼
     Yii fallback
          │ 404
          ▼
   Public template
          │
          ▼
     Response / 404

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[Copilot]

Pull request overview

Refactors site-request fallback handling to run through a single Laravel fallback route (instead of re-entering the HTTP kernel), with legacy Yii URL-rule compatibility handled via adapter middleware and related middleware pipeline simplifications.

Changes:

• Introduces a Laravel Route::fallback() controller (SiteRouteController) for site element matching, and updates template routing to only run on that fallback.
• Replaces DynamicRoute with a focused TemplateRoute, and updates legacy Yii rendering/dispatch to avoid re-entering the kernel.
• Reworks token/preview handling so previews are prepared during token middleware, and consolidates powered-by/schema-version handling into existing middleware.

Reviewed changes

Copilot reviewed 38 out of 38 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
yii2-adapter/tests-laravel/Http/LegacyMiddlewareTest.php	Adds coverage for legacy path normalization and middleware ordering (Yii fallback vs template fallback).
yii2-adapter/src/Yii2ServiceProvider.php	Reorders/injects global & group middleware to support legacy path normalization and Yii site fallback.
yii2-adapter/src/Http/NormalizeLegacyPath.php	New middleware that rewrites index.php?p=... requests without re-entering the app kernel.
yii2-adapter/src/Http/LegacyMiddleware.php	Removes recursive kernel re-entry for legacy index.php?p= requests.
yii2-adapter/src/Http/HandleYiiSiteRouteFallback.php	New middleware that runs Yii site URL-rule fallback on 404s from the Laravel site fallback route.
yii2-adapter/routes/web.php	Adjusts legacy CP/action route registration to align with new fallback + route caching constraints.
yii2-adapter/legacy/web/Application.php	Switches legacy rendering/dispatch to TemplateRoute and router dispatch (no kernel re-entry).
tests/Unit/Route/TemplateRouteTest.php	Updates unit tests to use TemplateRoute instead of DynamicRoute.
tests/Unit/Plugin/Concerns/HasRoutesTest.php	Adds assertions for route naming/serialization and route-cache behavior for plugin routes.
tests/Unit/Http/RequestMixinTest.php	Updates getHadToken expectations to reflect validated-token semantics.
tests/TestClasses/TestPlugin/src/Controllers/HasRoutesActionController.php	New invokable controller fixture for route serialization tests.
tests/TestClasses/TestPlugin/routes/actions.php	Switches test action route from closure to controller for serialization support.
tests/Feature/Http/Middleware/SetHeadersTest.php	Moves powered-by header assertions into SetHeaders middleware tests.
tests/Feature/Http/Middleware/SendPoweredByHeaderTest.php	Removes tests for deleted SendPoweredByHeader middleware.
tests/Feature/Http/Middleware/HandleTokenRequestTest.php	Expands coverage for token routing vs hidden action param behavior.
tests/Feature/Http/Middleware/HandleTemplateRequestTest.php	Adds test ensuring fixed-route 404s aren’t replaced by template fallback.
tests/Feature/Http/Middleware/CheckSchemaVersionTest.php	Removes tests for deleted CheckSchemaVersion middleware.
tests/Feature/Http/Middleware/CheckForUpdatesTest.php	Adds schema-compat behavior tests now handled by CheckForUpdates.
tests/Feature/Http/Controllers/SiteRouteControllerTest.php	Updates feature tests for new site fallback controller behavior and routing precedence.
tests/Feature/Http/Controllers/PreviewControllerTest.php	Updates preview behavior expectations now that preview targets aren’t directly routable.
src/Route/TemplateRoute.php	New dedicated template route handler.
src/Route/RouteServiceProvider.php	Adjusts middleware stack and project route registration behavior for route caching.
src/Route/DynamicRoute.php	Removes old dynamic route handler that re-entered the kernel.
src/Route/ControllerRoute.php	Refactors controller route execution to dispatch via the current routed request.
src/Plugin/Concerns/HasRoutes.php	Skips plugin route registration when routes are cached; adds naming prefix for site action routes.
src/Http/Routing/ActionRouteResolver.php	Prevents action-param override when a token route has already been resolved.
src/Http/PreviewRequestPreparer.php	New class to prepare preview placeholder elements during token handling.
src/Http/Mixins/RequestMixin.php	Changes getHadToken() semantics to only reflect validated/handled tokens.
src/Http/Middleware/SetHeaders.php	Moves powered-by header logic into SetHeaders and supports Symfony responses.
src/Http/Middleware/SendPoweredByHeader.php	Removes powered-by header middleware (logic moved into SetHeaders).
src/Http/Middleware/HandleTokenRequest.php	Updates token handling to prepare previews without kernel re-entry; adds route-resolved attribute.
src/Http/Middleware/HandleTemplateRequest.php	Ensures template fallback only runs for the site fallback route.
src/Http/Middleware/CheckSchemaVersion.php	Removes schema-version middleware (logic moved into CheckForUpdates).
src/Http/Middleware/CheckForUpdates.php	Adds schema-version compatibility enforcement.
src/Http/Controllers/SiteRouteController.php	Converts matched-element routing into the Laravel fallback controller path.
src/Http/Controllers/PreviewController.php	Removes preview action endpoint; preview is now driven via token middleware flow.
routes/web.php	Changes site fallback from abort(404) to SiteRouteController.
routes/actions.php	Removes direct preview/preview action route from token-required routes.