fix(i18n): give the Korean instruments their published source texts

The Korean questionnaire wording was translated freshly from English, so
a score built from it was comparable to nothing in the literature. Each
instrument now carries the text its own publisher put out, or no Korean
at all.

PHQ-9 and GAD-7 come verbatim from the instrument owner's distribution —
Pfizer's `PHQ9_Korean for Korea.pdf` (2010-06-15) and `GAD7_Korean for
Korea.pdf` (2010-05-18), the latter being the file Ahn/Kim/Choi 2019
names as what it validated. The sheets grant reproduction, translation,
display and distribution without permission. Verbatim means verbatim:
the spacing in "7 일 이상 방해 받았다" and the sheet's "안절부절 못하거나"
against the GAD-7 sheet's "안절부절못해서" are reproduced as printed.

WHO-5 has no official Korean arm. Neither the WHO's 2024 distribution
(26 languages) nor the Psychiatric Research Unit folder it inherited
from (31 languages) has ever carried one, and ePROVIDE lists the same
31. Korean therefore carries the published forward/back-translation
from Kim HJ et al., J Korean Geriatr Psychiatry 2010;14(2):90-96, which
is CC BY-NC and so redistributable; the attribution line names it. Its
validation sample was community-dwelling elderly rather than general
adults, which the definition says out loud.

The Sleep Condition Indicator reverts to English. It is validated in
English only, its cut-off was derived from those words, and no openly
redistributable Korean exists — so `ko` now matches de/es/fr/it/pl:
items, section stems and response anchors byte-identical to en.json,
under the localized "validated in English" note.

`ALL_APP_LOCALES` grows to seven, which is what stops the check-in
wizard claiming English wording over Korean items on every Korean
check-in.

One gap is deliberate and not yet resolved. The official Korean PHQ-9
and GAD-7 sheets disagree on anchor 2 — "7 일 이상 방해 받았다" against
"2 주 중 절반 이상 방해 받았다" — but both instruments read one shared
`mentalHealth.options` set, which holds for the other six locales
because their two sheets agree word for word. Korean takes the PHQ-9
wording for both here. GAD-7's anchors are therefore validated in
substance but not verbatim; splitting them into a `gad7Options`
namespace is the fix, and is left for the maintainer to weigh against
the 24 duplicated keys it would add across the other locales.

The functional-impairment item and its four anchors come from the same
PHQ-9 sheet. They are not scored and not covered by the
`validatedItemLocales` contract.

src/lib/mental-health/__tests__/instruments.test.ts

@@ -196,7 +196,7 @@ describe("mental-health instruments", () => {
     });
 
     it("declares validated item locales honestly (SCI = English only)", () => {
-      for (const locale of ["de", "en", "es", "fr", "it", "pl"]) {
+      for (const locale of ["de", "en", "es", "fr", "it", "pl", "ko"]) {
         expect(hasValidatedItems("WHO5", locale)).toBe(true);
         expect(hasValidatedItems("PHQ9", locale)).toBe(true);
       }

src/lib/mental-health/instruments.ts

@@ -11,8 +11,9 @@
  *   - PHQ-9: Kroenke 2001; GAD-7: Spitzer 2006 (public-domain Pfizer grant).
  *   - WHO-5: WHO/UCN/MSD/MHE/2024.1 (© WHO 2024, CC BY-NC-SA 3.0 IGO) — raw
  *     0–25, × 4 → 0–100; "a percentage score below 50 … an indication for
- *     further assessment". WHO publishes official translations for all six
- *     app locales; they ship verbatim.
+ *     further assessment". Six app locales ship the WHO/PRU translations
+ *     verbatim; Korean, which neither distribution carries, ships the
+ *     published Kim 2010 translation instead.
  *   - SCI: Espie et al., BMJ Open 2014;4:e004183 (© Sleepio Ltd, licensed
  *     free for non-commercial use, CC BY-NC) — 8 items, 0–4 each, total 0–32,
  *     HIGHER = better sleep; "a score of ≤16 … seems reasonable to detect
@@ -98,7 +99,7 @@ export interface InstrumentDefinition {
   attribution: string;
 }
 
-const ALL_APP_LOCALES = ["de", "en", "es", "fr", "it", "pl"] as const;
+const ALL_APP_LOCALES = ["de", "en", "es", "fr", "it", "pl", "ko"] as const;
 
 /**
  * The PHQ family is public-domain (Pfizer 2010); this is the canonical footer
@@ -188,11 +189,17 @@ const WHO5: InstrumentDefinition = {
   actionThreshold: 50,
   safetyItemIndex: null,
   // WHO publishes official de/en/es/fr/it/pl versions — all bundled verbatim.
+  // There is no Korean one, so `ko` carries the published forward/back-
+  // translation from Kim 2010 instead, which is CC BY-NC and so
+  // redistributable. Its validation sample was community-dwelling elderly,
+  // not general adults — narrower than the other six arms.
   validatedItemLocales: ALL_APP_LOCALES,
   attribution:
     "World Health Organization. The World Health Organization-Five Well-Being " +
     "Index (WHO-5). Geneva: World Health Organization; 2024. Licence: " +
-    "CC BY-NC-SA 3.0 IGO. WHO does not endorse this application.",
+    "CC BY-NC-SA 3.0 IGO. WHO does not endorse this application. Korean " +
+    "translation: Kim HJ, Moon YS, Son BK, Lee SK, Rho HJ, Kim DH. J Korean " +
+    "Geriatr Psychiatry 2010;14(2):90-96 (CC BY-NC 3.0).",
 };
 
 /**