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>

tests/functional/web_api.spec.ts

@@ -61,6 +61,16 @@ test.group('Web API', (group) => {
     assert.notInclude(await ids({ ext: 'iso' }), id)
     // "sho" is part of "show", not an extension.
     assert.notInclude(await ids({ ext: 'sho' }), id)
+
+    // A plainly posted file counts too, not only archive entries; volumes count as their archive.
+    const now = new Date()
+    await FileStore.insert([
+      { filename: 'Webtest.Show.S01E02.1080p.nfo', poster: 'p', date: now.getTime(), parts: 1, size: 10, release_id: id, groups: '[]', segments: [], created_at: now, updated_at: now },
+      { filename: 'Webtest.Show.S01E02.1080p.7z.002', poster: 'p', date: now.getTime(), parts: 1, size: 10, release_id: id, groups: '[]', segments: [], created_at: now, updated_at: now },
+    ])
+    assert.include(await ids({ ext: 'nfo' }), id)
+    assert.include(await ids({ ext: '7z' }), id)
+    assert.deepEqual((await db.from('releases').where('id', id).first()).extensions, ['7z', 'mkv', 'nfo'])
   })
 
   test('serves an NZB with the real file name', async ({ client, assert }) => {