feat(calendar): image/attachment per event, direct links, copy link, ImageModal component

- calendar_item schema: flyer → image (type: image), attachment (assetUrl)
- CalendarItemData: image + attachment fields
- event anchor IDs (#event-{slug}) with onMount hash scroll + auto-open
- share button uses direct calendar anchor URL
- copy link button (mdi:link-variant) copies anchor URL to clipboard
- ImageModal extracted as reusable component
- action buttons always show text (no expand-on-hover)
- onDestroy window guard (SSR fix)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/iconify-mdi-subset.generated.json

@@ -69,6 +69,12 @@
     "map-marker-outline": {
       "body": "<path fill=\"currentColor\" d=\"M12 6.5A2.5 2.5 0 0 1 14.5 9a2.5 2.5 0 0 1-2.5 2.5A2.5 2.5 0 0 1 9.5 9A2.5 2.5 0 0 1 12 6.5M12 2a7 7 0 0 1 7 7c0 5.25-7 13-7 13S5 14.25 5 9a7 7 0 0 1 7-7m0 2a5 5 0 0 0-5 5c0 1 0 3 5 9.71C17 12 17 10 17 9a5 5 0 0 0-5-5\"/>"
     },
+    "magnify-plus": {
+      "body": "<path fill=\"currentColor\" d=\"M9 2a7 7 0 0 1 7 7c0 1.57-.5 3-1.39 4.19l.8.81H16l6 6l-2 2l-6-6v-.59l-.81-.8A6.9 6.9 0 0 1 9 16a7 7 0 0 1-7-7a7 7 0 0 1 7-7M8 5v3H5v2h3v3h2v-3h3V8h-3V5z\"/>"
+    },
+    "file-download": {
+      "body": "<path fill=\"currentColor\" d=\"M14 2H6c-1.11 0-2 .89-2 2v16c0 1.11.89 2 2 2h12c1.11 0 2-.89 2-2V8zm-2 17l-4-4h2.5v-3h3v3H16zm1-10V3.5L18.5 9z\"/>"
+    },
     "download": {
       "body": "<path fill=\"currentColor\" d=\"M5 20h14v-2H5m14-9h-4V3H9v6H5l7 7z\"/>"
     },