feat: announce Homarr v2 beta (#6793)

* feat: announce Homarr v2 beta

* chore: refine v2 beta announcement

* feat: expand v2 beta guidance

* chore: refine v2 beta resources

* chore: simplify v2 beta modal

* chore: improve v2 beta feedback links

* fix: keep v2 modal above header

* chore: sharpen v2 beta message

* fix: clear header for v2 modal

packages/definitions/src/cookie.ts

@@ -1,2 +1,3 @@
 export const colorSchemeCookieKey = "homarr.color-scheme";
 export const localeCookieKey = "homarr.locale";
+export const v2BetaAnnouncementCookieKey = "homarr.v2-beta-announcement";