The garden learns which language a card is in, and read-aloud stops guessing

Phase 28 (c), the last of the phase. A word met inside a Portuguese
document is a Portuguese card: migration 0018 mirrors documents.doc_lang
onto vocab_words, set server-side from the ownership lookup capture was
already making. Every card still reviews — filtering the queue to the
half she is learning would drop the words she actually met.

Read-aloud was the larger surprise. detectLang routed Han/kana to
Chinese and everything else to en-US, so the zh pair was accidentally
right and every Latin pair wrong. doc_lang now reaches the client
read-only on the document JSON, and docLang(text, verdict) answers for a
passage taken out of it — with the script test still winning, because
quoted Chinese must never be spelled out one "Chinese letter" at a time.

Claude-Session: https://claude.ai/code/session_01GJHNvirh7Hzhc9RL3HAvz7

web/src/audio/speech.test.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest'
-import { nativeLang, speak, stopSpeech } from './speech'
+import { docLang, nativeLang, speak, stopSpeech } from './speech'
 import { resetPackForTests, setPackLang } from '../i18n'
 
 // Read-aloud has two jobs beyond "make a sound": ask for the right pace, and ask
@@ -85,3 +85,33 @@ describe('nativeLang', () => {
     expect(bodies.at(-1)).toMatchObject({ text: 'chat', lang: 'fr-FR' })
   })
 })
+
+describe('docLang', () => {
+  // The document's verdict is the answer for a passage lifted out of it, because
+  // for a Latin pair there is no other answer available: an English sentence and
+  // a Portuguese one are the same letters.
+  it('reads a flipped document in her own language', () => {
+    setPackLang('pt-PT')
+    expect(docLang('Ontem foi difícil.', 'pair')).toBe('pt-PT')
+  })
+
+  it('reads an English document in English, and treats the backfill as English', () => {
+    setPackLang('pt-PT')
+    expect(docLang('Yesterday was hard.', 'en')).toBe('en-US')
+    expect(docLang('Yesterday was hard.', '')).toBe('en-US')
+  })
+
+  it('lets the script win over the verdict, so quoted Chinese is never spelled out', () => {
+    // An English document quoting Chinese is 'en' by verdict, and the English
+    // voice reads Han characters one "Chinese letter" at a time — the one
+    // failure worse than silence.
+    setPackLang('zh')
+    expect(docLang('你好世界', 'en')).toBe('zh-CN')
+  })
+
+  it('is what the editor selection and the garden card ask for', () => {
+    setPackLang('fr')
+    speak('Le chat dort.', docLang('Le chat dort.', 'pair'))
+    expect(bodies.at(-1)).toMatchObject({ text: 'Le chat dort.', lang: 'fr-FR' })
+  })
+})