docs(12-01): complete browser language auto-detection and port autofill test fix

- SUMMARY.md created with TDD execution details and test results
- STATE.md updated with decisions and session info
- ROADMAP.md updated: Phase 12 now shows 1/2 summaries (In Progress)

.planning/STATE.md

@@ -4,6 +4,22 @@ milestone: v1.1
 milestone_name: Hardening & Validation
 current_plan: 3
 status: verifying
+stopped_at: Completed 12-i18n-bugfixes/12-01-PLAN.md
+last_updated: "2026-04-15T13:45:02.158Z"
+last_activity: 2026-04-15
+progress:
+  total_phases: 5
+  completed_phases: 4
+  total_plans: 20
+  completed_plans: 19
+---
+
+---
+gsd_state_version: 1.0
+milestone: v1.1
+milestone_name: Hardening & Validation
+current_plan: 3
+status: Phase complete — ready for verification
 stopped_at: Completed 11-ui-enhancements/11-04-PLAN.md
 last_updated: "2026-04-15T13:08:42.940Z"
 last_activity: 2026-04-15
@@ -61,6 +77,11 @@ Last activity: 2026-04-15
 - Phase 9: UX Tech Debt Closure (UX-01..03) — must land before rollout
 - Phase 10: Real-World Runtime Validation (RTVAL-01..05) — must pass before rollout
 - Phase 11: UI Enhancements (UIE-01..05) — printer edit, separated form/list, client nav, theme toggle, i18n FR/EN
+- Phase 12: i18n bugfixes — full translation coverage + browser language auto-detection
+
+### Roadmap Evolution
+
+- Phase 12 added: i18n bugfixes — untranslated buttons/labels found post-Phase 11; browser language setting not honoured
 
 ### Open Concerns (now owned by v1.1 phases)
 
@@ -107,6 +128,8 @@ Full decision log in PROJECT.md Key Decisions table. Milestone v1.0 decisions ar
 - [Phase 11-ui-enhancements]: 11-01: driver_data context kept in GET /printers handler for future Plan 02 edit modal
 - [Phase 11-ui-enhancements]: 11-04: client_id extracted from printers[0].client_id in Jinja2 — no grouped structure change needed
 - [Phase 11-ui-enhancements]: 11-04: Unassigned group header plain text — group_client_id is None when client_id absent; no dead anchor
+- [Phase 12-i18n-bugfixes]: IIFE pattern chosen for Alpine store lang init — evaluates at store creation time (inside alpine:init), before any hydration
+- [Phase 12-i18n-bugfixes]: playwright browser.new_context(locale=...) used for navigator.language tests — isolates locale per test without global fixture contamination
 
 ### Active Blockers
 
@@ -120,6 +143,6 @@ None. BLOCKER-01 resolved 2026-04-13 via commits 74535ea (HMAC over IV+ciphertex
 
 ## Session Continuity
 
-Last session: 2026-04-15T12:54:00.369Z
-Stopped at: Completed 11-ui-enhancements/11-04-PLAN.md
+Last session: 2026-04-15T13:45:02.151Z
+Stopped at: Completed 12-i18n-bugfixes/12-01-PLAN.md
 Resume file: None