Extension filter via a releases.extensions column

The first version matched extensions in search_text, which was wrong and
slow: file names enter search_text as stems without extension (so plainly
posted .mkv files were missed), and matching the TOASTed text took 3-4 s
for common types.

- Migration …130: releases.extensions text[] (two to four characters with
  a letter; .7z.001 and .r00 count as 7z and rar), kept current by triggers
  on files (name, release) and on releases (archive listing), filled with
  one sequential pass over files, with a GIN index.
- Search: ext matches with `extensions && ?`.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

database/schema.ts

@@ -300,7 +300,7 @@ export class ReleaseFileSchema extends BaseModel {
 }
 
 export class ReleaseSchema extends BaseModel {
-  static $columns = ['category', 'complete', 'container', 'contents', 'encrypted', 'fileCount', 'fileTotal', 'firstSeenAt', 'groups', 'id', 'lastSeenAt', 'name', 'password', 'passwordSource', 'postedAt', 'poster', 'releaseKey', 'searchFiles', 'searchText', 'size', 'source'] as const
+  static $columns = ['category', 'complete', 'container', 'contents', 'encrypted', 'extensions', 'fileCount', 'fileTotal', 'firstSeenAt', 'groups', 'id', 'lastSeenAt', 'name', 'password', 'passwordSource', 'postedAt', 'poster', 'releaseKey', 'searchFiles', 'searchText', 'size', 'source'] as const
   $columns = ReleaseSchema.$columns
   @column()
   declare category: number | null
@@ -313,6 +313,8 @@ export class ReleaseSchema extends BaseModel {
   @column()
   declare encrypted: boolean | null
   @column()
+  declare extensions: any | null
+  @column()
   declare fileCount: number
   @column()
   declare fileTotal: number | null