Phase 21: Petal learns to be an English+Portuguese pair

The plan said "Hunspell pt-PT vendored like en-US". Measuring that first is
what saved it: nspell expands affixes eagerly on construction, and European
Portuguese's 1,340 rules over 44,257 stems want over a gigabyte of browser
heap — ~340 MB for the first 12,000 entries, and no return at all after three
minutes on the whole file. So the expansion runs once at build time instead:
1,039,058 forms, 2.66 MB gzipped, read by the same nspell in 842 ms.

The obvious npm package would also have shipped the wrong language. Both
dictionary-pt and dictionary-pt-br carry VERO, the Brazilian word list, so
vendoring by name puts pt-BR spellings behind a pt-PT label — the drift
SUGGESTIONS §3 warns about, arriving through the packaging where no reviewer
can see it. The source is Projecto Natura's, and the build script now asserts
the fault lines (receção in, recepção out) before writing anything.

Spellcheck consults both dictionaries and flags only what both reject, which
is the no-detector answer to a pair with no script boundary. The word card
does the same in the other direction: "data" is a word in both languages, so
Petal shows both readings rather than guessing which she meant.

Writing the tests caught the one real bug — extendedAlphabet was a snapshot
while correct/suggest read live, and her dictionary arrives after English, so
every lookup would have resolved "cora" while the underlines were already
right.

Not done, and not claimed: the pack has not been read by a pt-PT speaker, and
the Piper voice is deferred with the deploy.

Claude-Session: https://claude.ai/code/session_016y6gyuHkQXPiEuW8RGQyua

web/src/api/client.ts

@@ -78,12 +78,27 @@ export interface WordInfo {
   frequency: number
   difficulty: number
   etymology: string // free-form, already trimmed to a line by the server; '' when absent
+  // The same token read as a word of the writer's own language, when it is one.
+  // Absent for a zh-pair writer and for almost every word in a Latin pair — see
+  // lexicon.Reverse for why Petal asks both directions instead of guessing.
+  reverse?: WordReverse
+}
+
+// A word looked up in the other direction: the writer's language -> English.
+export interface WordReverse {
+  lang: string
+  gloss: string
+  definitions?: WordMeaning[]
+  phonetic?: string
 }
 
 // The lightweight Chinese-only gloss behind the inline hover/select tooltip.
 export interface Gloss {
   word: string
   gloss: string
+  // The English meaning of the token read as a word of her own language.
+  // Present only on a collision (Portuguese *sale*, French *chat*).
+  reverse?: string
 }
 
 export type SuggestionType = 'grammar' | 'phrasing' | 'idiom' | 'clarity' | 'voice' | 'collocation' | 'mechanics'