feat(1.x): reload once when a route chunk fails to load

[lxsmnsyc]

Closes #1644 on the 1.x line. Same change as #2348 on main.

When a deploy replaces a route's chunk while a page is open, navigating to that route fails to import its component. The page ends on "Error | Uncaught Client Exception" until the user refreshes by hand.

Change

• lazyRoute's production branch wraps component.import() with withRouteChunkReload, in the browser only. The wrapper is the same as on main. On a failed import it checks a 10-second loop guard in sessionStorage, resolves with an empty component so the router finishes the navigation, and reloads once location.href is the destination. It falls back to reloading after 1 second. A second failure within the window is rethrown. feat(router): reload once when a route chunk fails to load #2348 explains why it resolves instead of staying pending.
• A new reloadOnRouteChunkError option in defineConfig, on by default, passed to the client through define in all three routers, the same way as devOverlay. It is typed in config/index.d.ts and env.d.ts.
• 1.x needs this inside lazyRoute rather than through Vite's vite:preloadError event. 1.x loads route components with a computed import(MANIFEST.client.inputs[...].output.path), which does not go through Vite's preload helper, so that event never fires for route chunks here. I checked this in a production build.

Testing

A real deploy on the 1.x basic fixture, production build. Build v1 and open /. Then stop the server, change about.tsx, build v2, restart on the same port, and click About in the open v1 tab:

Build	Reloads	Final URL	Page
origin/1.x	0	/about	"Error | Uncaught Client Exception"
this change	1	/about	the v2 /about
this change, reloadOnRouteChunkError: false	0	/about	"Error | Uncaught Client Exception"
this change, chunk still missing after the reload	1	/about	no second reload

• New route-chunk-reload.spec.ts (6 tests), the same as on main.
• @solidjs/start test:ci (101 tests) and typecheck pass. apps/tests build, unit:ci and the full Cypress suite against the production build (19) pass.

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