docs(07-02): complete frontend i18n infrastructure plan

- Create 07-02-SUMMARY.md with full execution details
- Update STATE.md with position, decisions, metrics
- Update ROADMAP.md progress (Phase 7: 2/4 plans complete)
- Mark requirements I18N-01, I18N-02 complete in REQUIREMENTS.md

.planning/STATE.md

@@ -3,14 +3,14 @@ gsd_state_version: 1.0
 milestone: v1.0
 milestone_name: milestone
 status: completed
-stopped_at: Completed 07-01-PLAN.md
-last_updated: "2026-03-25T22:28:47.475Z"
+stopped_at: Completed 07-multilanguage-02-PLAN.md
+last_updated: "2026-03-25T22:30:25.808Z"
 last_activity: 2026-03-23 — Completed 03-02 onboarding wizard, Slack OAuth, BYO API keys
 progress:
   total_phases: 7
   completed_phases: 6
   total_plans: 29
-  completed_plans: 26
+  completed_plans: 27
   percent: 100
 ---
 
@@ -78,6 +78,7 @@ Progress: [██████████] 100%
 | Phase 06-web-chat PP02 | 6min | 2 tasks | 10 files |
 | Phase 06-web-chat P03 | verification | 1 tasks | 0 files |
 | Phase 07-multilanguage P01 | 7min | 2 tasks | 12 files |
+| Phase 07-multilanguage P02 | 9min | 2 tasks | 14 files |
 
 ## Accumulated Context
 
@@ -173,6 +174,9 @@ Recent decisions affecting current work:
 - [Phase 07-multilanguage]: Translation overlay at response time (not stored) — English values never overwritten in DB
 - [Phase 07-multilanguage]: auth/verify response includes language field — Auth.js JWT can carry it without additional per-request DB queries
 - [Phase 07-multilanguage]: PortalUser.language server_default='en' — existing users get English without data migration
+- [Phase 07-multilanguage]: i18n/locales.ts created to separate client-safe constants from server-only i18n/request.ts (next/headers import)
+- [Phase 07-multilanguage]: Cookie name konstruct_locale for cookie-based locale with no URL routing
+- [Phase 07-multilanguage]: LanguageSwitcher isPreAuth prop skips DB PATCH and session.update() on login page
 
 ### Roadmap Evolution
 
@@ -188,6 +192,6 @@ None — all phases complete.
 
 ## Session Continuity
 
-Last session: 2026-03-25T22:28:47.472Z
-Stopped at: Completed 07-01-PLAN.md
+Last session: 2026-03-25T22:30:25.805Z
+Stopped at: Completed 07-multilanguage-02-PLAN.md
 Resume file: None