feat(ui): establish Settings page layout primitives

job-tracker-ui/src/theme.ts

@@ -218,6 +218,10 @@ function buildTypography() {
   return {
     fontFamily: "'Archivo', system-ui, -apple-system, Segoe UI, Roboto, Helvetica Neue, Arial, sans-serif",
     letterSpacing: 0,
+    // Opt-in application hierarchy; legacy page/marketing variants stay unchanged.
+    pageTitle: { fontWeight: 700, fontSize: "1.5rem", lineHeight: 1.25, letterSpacing: "-0.01em", "@media (min-width: 768px)": { fontSize: "1.75rem", lineHeight: 34 / 28 } },
+    sectionTitle: { fontWeight: 600, fontSize: "1.125rem", lineHeight: 24 / 18 },
+    pageDescription: { fontWeight: 400, fontSize: "0.875rem", lineHeight: 20 / 14 },
     // Mockup headings (F:\Pictures\website\jobtracker\new) are bold/black-weight display
     // type ("Dashboard", "One workspace for the whole search") -- 500 across the board read
     // as noticeably lighter/flatter than that reference. h1-h4 (page titles, hero, section
@@ -283,6 +287,9 @@ export const getTheme = (_mode: "light" | "dark") => {
           "--app-page-gutter": "16px",
           "--app-section-gap": "24px",
           "--app-card-padding": "16px",
+          "--app-page-width-reading": "60rem",
+          "--app-page-width-data": "82.5rem",
+          "--app-page-width-editor": "100%",
         },
         "@media (min-width: 768px)": {
           ":root": {