feat(coach,admin): finish the self-context and invite surfaces end to end

Invites move into their own admin section with a real ledger: status
badges, expiry, uses, a redemption history of who joined when (new
redemption table, revocation is now soft so history survives), and an
honest one-time link/QR moment. The assistant self-context grows
structured fields for conditions, allergies and focus — encrypted like
the free text — merges age and gender from the profile into one fenced
prompt block, and asks up to three targeted follow-up questions that
surface as tappable chips above the coach composer. A fourth nudge
trigger gently suggests a check-up when the self-context is stale and
the coach is actually in use.

src/components/admin/admin-shell.tsx

@@ -32,6 +32,7 @@ import {
   ShieldAlert,
   SlidersHorizontal,
   Sparkles,
+  Ticket,
   Users,
   type LucideIcon,
 } from "lucide-react";
@@ -104,6 +105,13 @@ export const ADMIN_SECTIONS: readonly AdminSection[] = [
     titleKey: "admin.section.users.title",
     icon: Users,
   },
+  // v1.16.0 — invites as their own section, directly after Users
+  // (admission lives next to the accounts it creates).
+  {
+    slug: "invites",
+    titleKey: "admin.section.invites.title",
+    icon: Ticket,
+  },
   {
     slug: "api-tokens",
     titleKey: "admin.section.api-tokens.title",