fix(02): resolve 3 typecheck errors and i18n langDir path

- useSetLocale → destructured setLocale from useI18n()
- addSeoAttributes → seo option for useLocaleHead()
- process.env → import.meta.env for Nuxt compatibility
- langDir: 'locales/' → 'app/locales/' (Nuxt 4 resolves from project root)

.planning/STATE.md

@@ -3,15 +3,15 @@ gsd_state_version: 1.0
 milestone: v1.0
 milestone_name: milestone
 status: executing
-stopped_at: Completed 02-02-PLAN.md
-last_updated: "2026-04-08T14:26:56.840Z"
-last_activity: 2026-04-08 -- Phase 2 planning complete
+stopped_at: Phase 2 execution complete — pending verification
+last_updated: "2026-04-08T16:00:00.000Z"
+last_activity: 2026-04-08 -- Phase 2 all 3 plans executed
 progress:
   total_phases: 3
-  completed_phases: 2
+  completed_phases: 1
   total_plans: 5
   completed_plans: 5
-  percent: 100
+  percent: 66
 ---
 
 # Project State
@@ -21,16 +21,16 @@ progress:
 See: .planning/PROJECT.md (updated 2026-04-07)
 
 **Core value:** Chaque page du portfolio doit être crawlable par les moteurs de recherche sans JavaScript côté client
-**Current focus:** Phase 1 — Foundation
+**Current focus:** Phase 2 — SSR Shell (execution complete)
 
 ## Current Position
 
 Phase: 2 of 3 (ssr shell)
-Plan: Not started
-Status: Ready to execute
-Last activity: 2026-04-08 -- Phase 2 planning complete
+Plan: 3/3 complete
+Status: Executed — pending verification
+Last activity: 2026-04-08 -- Phase 2 all 3 plans executed
 
-Progress: [░░░░░░░░░░] 0%
+Progress: [██████░░░░] 66%
 
 ## Performance Metrics