Changes

• A locale-prefixed request for an on-demand page that only exists in the fallback locale (/de/live with fallback: { de: 'en' }) was answered with status 302, the page body and no Location. getDefaultStatusCode assigns that 302 to a page reached through one of its fallbackRoutes, and since fix(i18n): only trigger fallback for 404 responses #15704 nothing consumed it: finalizeI18n only treats the fallback route type as a miss, and such a page has type page.
• finalizeI18n now treats that render like the fallback sentinel, so computeFallbackRoute rewrites or redirects per fallbackType. A page that took over the response (an explicit redirect or status) is still left alone, which keeps [i18n] Fallback middleware intercepts 3xx redirects from page handlers, should only trigger on 404 #15688 fixed.

Fixes #18473

Testing

• test/units/i18n/i18n-app.test.ts: on-demand route reached through a fallback route with rewrite (200, body) and redirect (302 + Location); a redirect or status set by the page is preserved.
• test/units/routing/routing-helpers.test.ts: the extracted isFallbackRouteMatch helper.
• test/i18n-fallback-on-demand.test.ts with the i18n-fallback-on-demand fixture: full build with the test adapter for both fallback types; the prerendered fallback page assertions document the build path, which was not affected.

Docs

No docs update needed: this restores the documented fallbackType behavior for on-demand pages.