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/api/client.ts

@@ -44,8 +44,18 @@ export interface Document {
   // When true, this document's automatic snapshots are never pruned, so its
   // full writing trail survives as authorship evidence (see the passport).
   preserve_history: boolean
+  // Which language this document is written in, as decided server-side by the
+  // checkpoint pass: '' | 'en' | 'pair' ('' reads as English). Read-only — the
+  // editor never sends it. It is here so read-aloud can use the right voice on a
+  // document written in her own language.
+  doc_lang: DocLang
 }
 
+// The document-language verdict, shared by documents and garden cards. 'pair'
+// names the writer's own language rather than a language code, so changing her
+// pair re-reads her documents instead of stranding a stale name on them.
+export type DocLang = '' | 'en' | 'pair'
+
 // Fields the editor sends on auto-save. All optional so a rename can send title
 // alone; the editor sends the full set.
 export interface DocUpdate {
@@ -125,6 +135,9 @@ export interface VocabWord {
   phonetic: string
   example: string
   doc_id: string | null
+  // The language of the document this word was met in — the card's own language
+  // (migration 0018). Read-aloud needs it: "comum" is unguessable from letters.
+  lang: DocLang
   due_at: string
   interval_days: number
   ease: number