chore(i18n): drop 380 dead translation keys flagged in W10 runtime probe

W10's i18n-runtime-gaps probe inventoried 405 unreferenced catalog keys
across both locale files. A second-pass verification against the source
tree (literal `"key"` / `'key'` / backtick exact-match) confirmed 380 of
them as truly orphan and 25 as live references the static analyser had
missed — typically built through template literals or wrapped in
non-string contexts.

This commit removes the 380 verified-dead keys from all six locale
files (en/de/fr/es/it/pl) and prunes the now-empty
`classifications.{bp,pulse,bodyFat}.*` placeholder allow-list entries
in `i18n-locale-integrity.test.ts` so the parity test passes against
the smaller surface.

Top namespaces retired:
  settings.*            (114 keys) — old setup screens, audit-log
                                     leaf labels, ai providerChain
                                     scaffolding
  classifications.*     (69 keys)  — alerts.* group + legacy per-metric
                                     leaf labels; live classification
                                     surfaces use targets.* now
  admin.*               (38 keys)  — superseded by admin/[section] shell
  onboarding.*          (21 keys)  — v1.4.22 onboarding rewrite leftovers
  medications.*         (18 keys)  — v1.4.18 redesign orphans
  dashboard.*           (15 keys)  — v1.4.20 insights redesign leftovers
  bugreport.*           (12 keys)  — simplified bug-report screen
  common.*              (12 keys)  — generic strings no longer referenced
  charts.*              (15 keys)  — v1.4.20 chart-label slugs
  auth.*                (10 keys)  — auth UI now uses inline copy
  notifications.*       (10 keys)  — toast variants no longer fired
  targets.*             (9 keys)   — replaced by targets.{label,status}.*
  measurements.*        (7 keys)
  comparison.*          (6 keys)
  mood.*                (5 keys)
  thresholds.*          (4 keys)
  achievements.*        (4 keys)
  format.*              (3 keys)
  gettingStarted.*      (2 keys)
  nav.*                 (1 key)

Verification:
  pnpm typecheck                  → clean
  pnpm lint                       → clean
  pnpm vitest run                 → 3731 passed, 1 skipped
  i18n-locale-integrity           → 26 / 26 (locales still parity-clean)

src/lib/__tests__/i18n-locale-integrity.test.ts

@@ -241,10 +241,6 @@ describe("i18n locale file integrity", () => {
   // See `docs/audit/v1415-i18n-coverage.md` §Legitimate EN==DE==key cases.
   const PLACEHOLDER_ALLOWLIST = new Set<string>([
     "settings.ntfy",
-    "classifications.bp.Optimal",
-    "classifications.bp.Normal",
-    "classifications.pulse.Normal",
-    "classifications.bodyFat.Fitness",
     // v1.4.19 phase A7 — "BMI" is the same acronym in EN and DE,
     // and the medical / fitness "Optimal", "Fitness", "Normal"
     // categories are technical terms that German clinics also use