feat: preload logged-in user profile image for offline access

Preload profile images when profiles are fetched and when displayed
in the sidebar to ensure they're cached by the Service Worker for
offline access.

src/components/SidebarHeader.tsx

@@ -7,6 +7,7 @@ import { useEventModel } from 'applesauce-react/hooks'
 import { Models } from 'applesauce-core'
 import IconButton from './IconButton'
 import { faBooks } from '../icons/customIcons'
+import { preloadImage } from '../hooks/useImageCache'
 
 interface SidebarHeaderProps {
   onToggleCollapse: () => void
@@ -36,6 +37,13 @@ const SidebarHeader: React.FC<SidebarHeaderProps> = ({ onToggleCollapse, onLogou
 
   const profileImage = getProfileImage()
 
+  // Preload profile image for offline access
+  useEffect(() => {
+    if (profileImage) {
+      preloadImage(profileImage)
+    }
+  }, [profileImage])
+
   // Close menu when clicking outside
   useEffect(() => {
     const handleClickOutside = (event: MouseEvent) => {

src/services/profileService.ts

@@ -5,6 +5,7 @@ import { IEventStore } from 'applesauce-core'
 import { prioritizeLocalRelays, partitionRelays } from '../utils/helpers'
 import { rebroadcastEvents } from './rebroadcastService'
 import { UserSettings } from './settingsService'
+import { preloadImage } from '../hooks/useImageCache'
 
 /**
  * Fetches profile metadata (kind:0) for a list of pubkeys
@@ -65,6 +66,19 @@ export const fetchProfiles = async (
 
     const profiles = Array.from(profilesByPubkey.values())
 
+    // Preload profile images for offline access
+    for (const profile of profiles) {
+      try {
+        const profileData = JSON.parse(profile.content)
+        const picture = profileData.picture
+        if (picture) {
+          preloadImage(picture)
+        }
+      } catch {
+        // Ignore parse errors - profile content might be invalid JSON
+      }
+    }
+
     // Rebroadcast profiles to local/all relays based on settings
     if (profiles.length > 0) {
       await rebroadcastEvents(profiles, relayPool, settings)