feat: simplify resolveAvatarUrl — custom image first, gravatar fallback

Remove settings parameter. Always prefer user.image if available, otherwise
fall back to gravatar with d=404 to trigger AvatarFallback (initials) when
no gravatar exists. Removes support for avatarMode and dicebearStyle.

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

src/utils/resolve-avatar-url.ts

@@ -1,27 +1,12 @@
 import { createHash } from "crypto";
-import type { Setting } from "@/db/schema/01_setting";
 import type { User } from "@/db/schema/02_user";
 
 export function resolveAvatarUrl(
   user: Pick<User, "email" | "image">,
-  settings: Pick<Setting, "avatarMode" | "dicebearStyle"> | null | undefined,
 ): string | undefined {
-  const mode = settings?.avatarMode ?? "internal";
-
-  if (mode === "gravatar") {
-    const hash = createHash("md5")
-      .update((user.email ?? "").trim().toLowerCase())
-      .digest("hex");
-    return `https://www.gravatar.com/avatar/${hash}?s=200&d=mp`;
-  }
-
-  if (mode === "dicebear") {
-    const style = settings?.dicebearStyle ?? "thumbs";
-    const hash = createHash("md5")
-      .update((user.email ?? "").trim().toLowerCase())
-      .digest("hex");
-    return `https://api.dicebear.com/10.x/${style}/svg?seed=${hash}`;
-  }
-
-  return user.image ?? undefined;
+  if (user.image) return user.image;
+  const hash = createHash("md5")
+    .update((user.email ?? "").trim().toLowerCase())
+    .digest("hex");
+  return `https://www.gravatar.com/avatar/${hash}?s=200&d=404`;
 }