v3: fix migration 0011 mistaking real og:images for favicons

0011 tested for "favicon" anywhere in the path, so mirtitles.org's declared
og:image — /wp-content/uploads/2022/04/mir-logo-favicon.png — was moved into
faviconUrl and its thumbnailUrl cleared. Without a thumbnail, hasThumbnail() is
false and the journal mosaic demoted the dump from an image card to a
pull-quote. A blanket .svg match did the same to real artwork (tanibis.net's
header.svg).

0012 judges an icon by its filename rather than the whole path: named
favicon…/apple-touch-icon…/icon…, living in an icons/ directory, or ending in
.ico. That spares mir-logo-favicon.png and also catches icon_SEARCH.png, which
0011 missed. It runs in both directions, and is deliberately narrow when
reversing — a value is only promoted back to thumbnailUrl if it matched 0011's
rule but not this one, so rows written by a normal fetch aren't disturbed.

On the dev database: 4 thumbnails restored, 1 icon reclassified, real favicons
left alone, and a second pass rewrites nothing.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

api/db/migrate.ts

@@ -10,6 +10,7 @@ import { up as up0008ChatMessages } from "./migrations/0008_chat_messages.ts";
 import { up as up0009ChatReply } from "./migrations/0009_chat_reply.ts";
 import { up as up0010YoutubeEmbedStart } from "./migrations/0010_youtube_embed_start.ts";
 import { up as up0011SplitFaviconThumbnail } from "./migrations/0011_split_favicon_thumbnail.ts";
+import { up as up0012FixFaviconReclassification } from "./migrations/0012_fix_favicon_reclassification.ts";
 
 interface Migration {
   name: string;
@@ -31,6 +32,10 @@ const MIGRATIONS: Migration[] = [
   { name: "0009_chat_reply", up: up0009ChatReply },
   { name: "0010_youtube_embed_start", up: up0010YoutubeEmbedStart },
   { name: "0011_split_favicon_thumbnail", up: up0011SplitFaviconThumbnail },
+  {
+    name: "0012_fix_favicon_reclassification",
+    up: up0012FixFaviconReclassification,
+  },
 ];
 
 export function runMigrations(db: DatabaseSync): void {