fix(concord): render the decrypted community icon (local file:// avatar)

A Concord community icon is CORD-02 §6 encrypted media: rememberConcordImageModel
fetches the ciphertext, AES-256-GCM-decrypts it, and caches the plaintext at a
local file:// path, which it hands to the avatar as the model. But
RobohashFallbackAsyncImage always wrapped the model in ProfilePictureUrl, and the
thumbnail-cache fetcher behind it (ProfilePictureFetcher) delegates a cache-miss
to Coil's http-only NetworkFetcher — so the file:// load failed and the row fell
back to the robohash, even though the icon had decrypted and cached correctly.

Only route remote http(s) pictures through the thumbnail cache; hand local/content
URIs straight to Coil's native fetchers, which load them directly. Verified
on-device: the Soapbox community icon now renders on the Messages rows and the
community header instead of a robohash.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/components/RobohashAsyncImage.kt

@@ -149,7 +149,16 @@ fun RobohashFallbackAsyncImage(
 
         val resources = LocalContext.current.resources
         SubcomposeAsyncImage(
-            model = ProfilePictureUrl(bridgedModel),
+            // The thumbnail-cache fetcher behind ProfilePictureUrl delegates to Coil's http-only
+            // NetworkFetcher, so a LOCAL model (e.g. a decrypted Concord community icon cached at
+            // file://) would fail there. Route only remote http(s) pictures through the thumbnail
+            // cache; hand local/content URIs to Coil's native fetchers, which load them directly.
+            model =
+                if (bridgedModel.startsWith("http://", ignoreCase = true) || bridgedModel.startsWith("https://", ignoreCase = true)) {
+                    ProfilePictureUrl(bridgedModel)
+                } else {
+                    bridgedModel
+                },
             contentDescription = contentDescription,
             modifier = modifier,
             alignment = alignment,