feat(nav): give the Coach a single primary nav home

The Coach is reachable from seven scattered entry points — a floating
button, the hero CTA, suggested-prompt chips, every metric empty state,
a per-metric icon, the conversations drawer — but it had no entry in the
nav. Power users found it instantly; a new user could miss the
differentiator entirely behind a 56px floating circle.

Add the Coach to the shared destination model as one labeled, primary
home, consistent with every other destination across desktop and mobile.
The existing entry points stay; this adds the front door they lacked.

messages/de.json

@@ -228,6 +228,7 @@
     "accountSettings": "Kontoeinstellungen",
     "mood": "Stimmung",
     "workouts": "Workouts",
+    "coach": "Coach",
     "skipToContent": "Zum Inhalt springen",
     "sidebar": "Sidebar",
     "mainNavigation": "Hauptnavigation",

messages/en.json

@@ -228,6 +228,7 @@
     "accountSettings": "Account settings",
     "mood": "Mood",
     "workouts": "Workouts",
+    "coach": "Coach",
     "skipToContent": "Skip to content",
     "sidebar": "Sidebar",
     "mainNavigation": "Main navigation",

messages/es.json

@@ -228,6 +228,7 @@
     "accountSettings": "Ajustes de cuenta",
     "mood": "Estado de ánimo",
     "workouts": "Entrenamientos",
+    "coach": "Coach",
     "skipToContent": "Saltar al contenido",
     "sidebar": "Barra lateral",
     "mainNavigation": "Navegación principal",

messages/fr.json

@@ -228,6 +228,7 @@
     "accountSettings": "Paramètres du compte",
     "mood": "Humeur",
     "workouts": "Entraînements",
+    "coach": "Coach",
     "skipToContent": "Aller au contenu",
     "sidebar": "Barre latérale",
     "mainNavigation": "Navigation principale",

messages/it.json

@@ -228,6 +228,7 @@
     "accountSettings": "Impostazioni account",
     "mood": "Umore",
     "workouts": "Allenamenti",
+    "coach": "Coach",
     "skipToContent": "Vai al contenuto",
     "sidebar": "Barra laterale",
     "mainNavigation": "Navigazione principale",

messages/pl.json

@@ -228,6 +228,7 @@
     "accountSettings": "Ustawienia konta",
     "mood": "Nastrój",
     "workouts": "Treningi",
+    "coach": "Coach",
     "skipToContent": "Przejdź do treści",
     "sidebar": "Pasek boczny",
     "mainNavigation": "Nawigacja główna",

src/components/layout/__tests__/nav-model.test.ts

@@ -16,9 +16,18 @@ import {
 } from "../nav-model";
 
 describe("nav-model destination list", () => {
-  it("lists Workouts as a first-class destination on both surfaces", () => {
+  it("lists Workouts and Coach as first-class destinations", () => {
     const hrefs = NAV_DESTINATIONS.map((d) => d.href);
     expect(hrefs).toContain("/insights/workouts");
+    expect(hrefs).toContain("/insights/coach");
+  });
+
+  it("gives the Coach exactly one nav home (F-3)", () => {
+    const coach = NAV_DESTINATIONS.filter(
+      (d) => d.href === "/insights/coach",
+    );
+    expect(coach).toHaveLength(1);
+    expect(coach[0]!.tKey).toBe("nav.coach");
   });
 
   it("orders the core spine: dashboard → measurements → mood → medications", () => {
@@ -57,6 +66,13 @@ describe("isNavDestinationActive most-specific resolution", () => {
     expect(isNavDestinationActive("/", "/measurements")).toBe(false);
   });
 
+  it("does not light up Insights when on its Coach sibling", () => {
+    expect(isNavDestinationActive("/insights/coach", "/insights/coach")).toBe(
+      true,
+    );
+    expect(isNavDestinationActive("/insights", "/insights/coach")).toBe(false);
+  });
+
   it("does not light up Insights when on its Workouts sibling", () => {
     expect(
       isNavDestinationActive("/insights/workouts", "/insights/workouts"),

src/components/layout/__tests__/sidebar-nav.test.tsx

@@ -131,24 +131,25 @@ describe("<SidebarNav> targets deprecation (v1.8.6)", () => {
   });
 });
 
-describe("<SidebarNav> unified destination model (v1.17.1 F-1)", () => {
-  it("surfaces Workouts as a first-class sidebar destination", () => {
-    // Pre-unify the sidebar hid Workouts entirely while the mobile bar
-    // promoted it. Both now render the one shared model, so both carry it.
+describe("<SidebarNav> unified destination model (v1.17.1 F-1 / F-3)", () => {
+  it("surfaces Workouts and the Coach as first-class sidebar destinations", () => {
+    // Pre-unify the sidebar hid Workouts entirely and had no Coach home,
+    // while the mobile bar promoted Workouts and still missed Coach. Both
+    // now render the one shared model, so both carry both destinations.
     const html = render();
     expect(html).toContain('href="/insights/workouts"');
+    expect(html).toContain('href="/insights/coach"');
     expect(html).toContain("Workouts");
+    expect(html).toContain("Coach");
   });
 
-  it("marks Workouts active without also marking Insights active", () => {
-    const html = render({ pathname: "/insights/workouts" });
-    // The Workouts link carries aria-current="page"; the Insights link,
-    // its less-specific sibling, must not (most-specific resolution).
-    const workouts = html.match(
-      /<a[^>]*href="\/insights\/workouts"[^>]*>/,
-    );
+  it("marks Coach active without also marking Insights active", () => {
+    const html = render({ pathname: "/insights/coach" });
+    // The Coach link carries aria-current="page"; the Insights link, its
+    // less-specific sibling, must not (most-specific resolution).
+    const coach = html.match(/<a[^>]*href="\/insights\/coach"[^>]*>/);
     const insights = html.match(/<a[^>]*href="\/insights"[^>]*>/);
-    expect(workouts?.[0]).toMatch(/aria-current="page"/);
+    expect(coach?.[0]).toMatch(/aria-current="page"/);
     expect(insights?.[0]).not.toMatch(/aria-current="page"/);
   });
 });

src/components/layout/nav-model.ts

@@ -5,6 +5,7 @@ import {
   FlaskConical,
   Home,
   Lightbulb,
+  MessagesSquare,
   Pill,
   Trophy,
   Waves,
@@ -87,6 +88,16 @@ export const NAV_DESTINATIONS: ReadonlyArray<NavDestination> = [
     icon: Lightbulb,
     tourId: "nav-insights",
   },
+  // v1.17.1 (F-3) — the Coach finally gets a single labeled nav home. It
+  // was reachable from seven scattered entry points (FAB, hero CTA, empty
+  // states, per-metric icons …) but nowhere in the nav, so a new user
+  // could miss the differentiator entirely. The other entry points stay.
+  {
+    href: "/insights/coach",
+    tKey: "nav.coach",
+    icon: MessagesSquare,
+    tourId: "nav-coach",
+  },
   {
     href: "/achievements",
     tKey: "nav.achievements",