Fixes avatar "never expire" timestamp being smaller than Date.now()

The V8 smi optimization (2^30) was applied to the avatar cache timestamp
in 2975af4, replacing Number.MAX_SAFE_INTEGER. Unlike the annotation
providers where the value is compared against line/column numbers, here
it is compared against Date.now() (~1.75 trillion ms), so the "never
expire" sentinel (~1.07 billion) always appears expired. This caused
repeated async re-lookups for repos with remotes but no integration.

Uses Infinity as the sentinel — makes hasAvatarExpired return false
without any arithmetic, and communicates the "never expire" intent
directly.

(#5155)

Author: sergeibbb

src/avatars.ts

@@ -20,8 +20,6 @@ import { configuration } from './system/-webview/configuration.js';
 import { getContext } from './system/-webview/context.js';
 import type { ContactPresenceStatus } from './vsls/vsls.js';
 
-const maxSmallIntegerV8 = 2 ** 30 - 1; // Max number that can be stored in V8's smis (small integers)
-
 let avatarCache: Map<string, Avatar> | undefined;
 const avatarQueue = new Map<string, Promise<Uri>>();
 
@@ -270,7 +268,7 @@ async function getAvatarUriFromRemoteProvider(
 		if (account?.avatarUrl == null) {
 			// If we have no account assume that won't change (without a reset), so set the timestamp to "never expire"
 			avatar.uri = undefined;
-			avatar.timestamp = maxSmallIntegerV8;
+			avatar.timestamp = Infinity;
 			avatar.retries = 0;
 
 			return undefined;