refactor(admin): consolidate assistant + feedback-quality into one Coach section

The ai-quality, assistant, and coach-feedback admin sections were three
separate navigation entries for one coherent coach-quality concern. Fold
them into a single "Coach" section that stacks the assistant surface
toggles, the server-key + module-availability operator config, and both
feedback-quality tables (Coach + Insights). Drop the three old slugs and
their section copy; add admin.section.coach.* across all six locales.

src/components/admin/__tests__/sections.test.tsx

@@ -155,7 +155,10 @@ describe("admin sections — SSR smoke", () => {
     expect(html).toContain("No feedback yet");
   });
 
-  it("admin slug list contains ai-quality (renderer parity)", () => {
-    expect(ADMIN_SECTION_SLUGS).toContain("ai-quality");
+  it("admin slug list contains coach (renderer parity)", () => {
+    // v1.18.1 — ai-quality / assistant / coach-feedback folded into one
+    // "coach" section. The standalone component still renders above; the
+    // slug parity assertion tracks the consolidated nav entry.
+    expect(ADMIN_SECTION_SLUGS).toContain("coach");
   });
 });

src/components/admin/admin-shell.tsx

@@ -23,14 +23,12 @@ import {
   Info,
   KeyRound,
   Inbox,
-  MessageSquare,
   Plug,
   Radio,
   ScrollText,
   Server,
   Settings,
   ShieldAlert,
-  SlidersHorizontal,
   Sparkles,
   Ticket,
   Users,
@@ -76,21 +74,14 @@ export const ADMIN_SECTIONS: readonly AdminSection[] = [
     titleKey: "admin.section.integrations.title",
     icon: Plug,
   },
+  // v1.18.1 — single "Coach" entry replacing the former ai-quality,
+  // assistant, and coach-feedback trio. The section body stacks all
+  // three surfaces so the coach-quality picture lives in one place.
   {
-    slug: "ai-quality",
-    titleKey: "admin.section.ai-quality.title",
+    slug: "coach",
+    titleKey: "admin.section.coach.title",
     icon: Sparkles,
   },
-  {
-    slug: "assistant",
-    titleKey: "admin.section.assistant.title",
-    icon: SlidersHorizontal,
-  },
-  {
-    slug: "coach-feedback",
-    titleKey: "admin.section.coach-feedback.title",
-    icon: MessageSquare,
-  },
   {
     slug: "feedback",
     titleKey: "admin.section.feedback.title",

src/components/admin/section-slugs.ts

@@ -14,13 +14,13 @@ export const ADMIN_SECTION_SLUGS = [
   "general",
   "services",
   "integrations",
-  "ai-quality",
-  // v1.4.31 — operator-side assistant feature-flag toggles. Sits
-  // between `ai-quality` (provider config) and `coach-feedback`
-  // (in-app feedback inbox) per
-  // `.planning/research/v15-assistant-optional.md` Part B.
-  "assistant",
-  "coach-feedback",
+  // v1.18.1 — the former `ai-quality`, `assistant`, and `coach-feedback`
+  // sections collapse into one "Coach" area. It holds the assistant
+  // surface toggles, the server-key + module-availability operator
+  // config, and both feedback-quality tables (Coach + Insights). Three
+  // navigation entries for one coherent coach-quality concern read as
+  // clutter; one card opens the full picture.
+  "coach",
   "feedback",
   "reminders",
   "users",