Sprint 132: LegalLayout LanguageSwitcher Mount

Decisions

Context: In Sprint 129, LanguageSwitcher was mounted at 4 locations with Suspense pattern (AppLayout L384/L464, AuthShell L43, LandingContent L80). In Sprint 131, TopNav was deleted → AppLayout unified. However, LegalLayout (/privacy, /terms) is a separate layout with no LanguageSwitcher mounted — language switching unavailable when visiting legal pages.
Choice: Added <Suspense fallback={null}><LanguageSwitcher /></Suspense> to the right side of the LegalLayout Nav. Applied justify-between to the nav container for Logo left / LanguageSwitcher right placement. Kept Server Component (async); Client Component (LanguageSwitcher) is automatically handled by RSC→CC boundary.
Verification: jest 1357 passing (+1), tsc/lint clean
Code Paths: frontend/src/components/layout/LegalLayout.tsx (+8 lines), frontend/src/components/layout/__tests__/LegalLayout.test.tsx (+11 lines, LanguageSwitcher mock + mount verification)
PR: #161 (fa1d68a, Squash merge)

Context: /guest, /guest/preview/[slug] (GuestNav), /shared/[token] (SharedLayout) also have LanguageSwitcher unmounted. Reconnaissance identified 5 candidates.
Choice: By user policy decision, only LegalLayout was fixed. Guest pages can switch language via LanguageSwitcher on Landing (/) before entry; Shared links are read-only views where toggling is not necessary.

Item	Value
Total changes	+19 lines, -2 lines (2 files)
jest	1357 passing (1356 → +1)
tsc	clean
lint	clean
Critic	Omitted (5th repetition of existing pattern, 0 new logic — same policy as Sprint 131)
PR	#161 Squash merge `fa1d68a`
Commits	2 (before squash: `29b6b8f` code + `ef5609d` ADR)
CI	31 pass / 7 skipping / 0 fail
end_commit	`fa1d68a`

Unprocessed operational debt from Sprint 130: