feat(ui): establish Settings page layout primitives

docs/roadmap/todo.md

@@ -4,11 +4,12 @@ Status reconciled: 2026-09-12.
 
 ## Current repository work
 
-- **P4-04 — not started:** review the completed [P4-03 preview keyboard checkpoint](../redesign/phase-4/p4-03/README.md) before the separately scoped page-layout/typography work. Preserve existing integrity coordination gates and regression coverage.
 - **P2-D01 — open:** repair the SQLite `DateTimeOffset` ordering baseline before package/tailoring restructuring; retain the expected-failure browser oracle until native capture and historical-binary preservation are proven. P2-O01's initial rules-500 behavior also remains unconfirmed.
 - **P3-O01/P3-O02 — open:** address analytics population/period labels and navigation/query/error retention when those surfaces are next changed. Evidence is in the current [redesign decision records](../redesign/phase-3/OPEN_DECISIONS.md).
 - **P4-02-D01–D04 — existing accessibility/content debt:** command-list semantic children, company save-error feedback outside the modal's accessible subtree, the mobile application-progress scroll region, and the literal AI context `{name}` placeholder. Evidence and owning future slices are in the [P4-02 record](../redesign/phase-4/p4-02/README.md). Do not disable modal background isolation or hide findings.
 - **P4-03-D01 — existing shared Tooltip contrast debt:** the light Redo tooltip fails the text contrast target. Evidence and the narrow regression exception are in the [P4-03 record](../redesign/phase-4/p4-03/README.md); repair in a scoped shared-theme follow-up.
+- **P4-04-O01 — existing fixed-toast overlap:** export-success feedback can temporarily obscure a bottom-of-page action. Review shared feedback placement with later shell work; P4-04 leaves timing/placement unchanged and verifies the action after normal dismissal. [Evidence](../redesign/phase-4/p4-04/README.md).
+- **P4-04-O02 — existing SQLite notification-save contention:** overlapping native preference read/write requests reproduced HTTP 500 with SQLite error 5 in two of ten local runs. The sequential UI test now awaits and requires the save response before readback; server concurrency remains unresolved. Investigate separately from page-layout/density work. [Evidence](../redesign/phase-4/p4-04/README.md).
 - **F04/B06 — open:** complete the authorized main release and production ingress/runtime verification; the browser gate and runner diagnostics remain unresolved. No gate should be bypassed.
 
 ## Delivery and feature gates
@@ -24,4 +25,4 @@ The current builder already includes expandable sections, preset/free-text custo
 
 CV preview margin, pagination and theme/template accuracy still require a dedicated rendering/PDF validation slice, as reiterated by Connor during P4-03. P4-03 only addresses the keyboard/viewport boundary. Define expected output and preserve current settings, templates and preview/PDF relationships before broader editor changes; do not restart already-completed builder features from archived plans.
 
-Completed phase items are intentionally omitted here; their evidence remains recoverable in the pre-cleanup backup and existing archive.
+Completed phase items are intentionally omitted here; their evidence remains in the current redesign checkpoint records and recoverable historical archive.