refactor(routes):

- keep install-mode root redirect to /install and add tests covering install root redirect and install page serving
- change root backend handler from Any("/") to POST("/") so GET / can consistently serve the SPA after install

Co-authored-by: Copilot <copilot@github.com>

src/www/assets/radio-group-8QacflxY.js

@@ -0,0 +1 @@
+import{Qu as e}from"./messages-BOl-zx8S.js";import{i as t}from"./button-D-oR8d6w.js";import{n,r,t as i}from"./dist-CML2zK1G.js";import{t as a}from"./createLucideIcon-DMX28cCu.js";var o=a(`circle`,[[`circle`,{cx:`12`,cy:`12`,r:`10`,key:`1mglay`}]]),s=e();function c({className:e,...n}){return(0,s.jsx)(r,{className:t(`grid gap-3`,e),"data-slot":`radio-group`,...n})}function l({className:e,...r}){return(0,s.jsx)(n,{className:t(`aspect-square size-4 shrink-0 rounded-full border border-input text-primary shadow-xs outline-none transition-[color,box-shadow] focus-visible:border-ring focus-visible:ring-[3px] focus-visible:ring-ring/50 disabled:cursor-not-allowed disabled:opacity-50 aria-invalid:border-destructive aria-invalid:ring-destructive/20 dark:bg-input/30 dark:aria-invalid:ring-destructive/40`,e),"data-slot":`radio-group-item`,...r,children:(0,s.jsx)(i,{className:`relative flex items-center justify-center`,"data-slot":`radio-group-indicator`,children:(0,s.jsx)(o,{className:`absolute top-1/2 left-1/2 size-2 -translate-x-1/2 -translate-y-1/2 fill-primary`})})})}export{l as n,c as t};