refactor(post-events): read event data from resolved calendarItem

Replace direct post.isEvent/eventDate/eventLocation reads with
getPostEventInfo() helper that derives info from the resolved
calendarItem reference. Loaders now resolve "calendarItem" and request
that field instead of legacy flat properties.

Also regenerate iconify mdi subset (map-marker-outline, download,
google, calendar-search, refresh).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/lib/components/BlogOverview.svelte

@@ -6,7 +6,7 @@
     import Tag from "./Tag.svelte";
     import Pagination from "./Pagination.svelte";
     import type { PostEntry } from "$lib/cms";
-    import { postHref } from "$lib/blog-utils";
+    import { postHref, getPostEventInfo } from "$lib/blog-utils";
     import { t as tStatic, T } from "$lib/translations";
     import type { Translations } from "$lib/translations";
     import {
@@ -34,8 +34,6 @@
         eventDate: string | null;
     };
 
-    type EventPost = PostEntry & { eventDate?: string; isEvent?: boolean };
-
     let {
         posts = [],
         tags = [],
@@ -56,7 +54,7 @@
         totalPosts?: number;
         basePath?: string;
         translations?: Translations | null;
-        upcomingEvents?: EventPost[];
+        upcomingEvents?: PostEntry[];
         searchIndex?: SearchIndexEntry[] | null;
     } = $props();
 
@@ -193,12 +191,13 @@
             </h2>
             <ul class="not-prose list-none space-y-2 pl-0">
                 {#each upcomingEvents as ev}
+                    {@const evInfo = getPostEventInfo(ev)}
                     <li>
                         <a
                             href={postHref(ev)}
                             class="group flex flex-wrap items-center gap-2 no-underline"
                         >
-                            <EventBadges eventDate={ev.eventDate} />
+                            <EventBadges eventDate={evInfo.eventDate} />
                             <span
                                 class="text-sm text-stein-900 group-hover:text-stein-900"
                                 >{ev.headline}</span