Add calendar summary to dashboard; default portal to 1hr inactivity timeout

Dashboard now shows today's and upcoming events (mine or all, toggle) for
users with calendar app access. Also gives the portal shell a 1-hour
inactivity default for devices that have never been configured, instead of
following child apps into an unlimited 30-day session — that's why the
dashboard could sit logged in for days without prompting. An explicit "Off"
choice in Admin Settings still overrides it (now written as mins=0 instead
of clearing the cookie, so it's distinguishable from "never configured").

src/pages/AdminSettings.tsx

@@ -861,10 +861,11 @@ function getInactivityMins(): number {
   return c ? parseInt(c.split('=')[1]) || 0 : 0
 }
 
+// Always writes the cookie, including for "Off" (mins=0) — this makes an
+// explicit Off choice distinguishable from a device that was never visited,
+// which the portal's own inactivity default relies on.
 function setInactivityMins(mins: number) {
-  document.cookie = mins > 0
-    ? `hnf_inactivity_mins=${mins}; max-age=31536000; path=/; SameSite=Strict`
-    : 'hnf_inactivity_mins=; max-age=0; path=/; SameSite=Strict'
+  document.cookie = `hnf_inactivity_mins=${mins}; max-age=31536000; path=/; SameSite=Strict`
 }
 
 function DeviceTab() {

src/pages/Dashboard.tsx

@@ -2,6 +2,7 @@ import { useNavigate } from 'react-router-dom'
 import { Download } from 'lucide-react'
 import { PageShell } from '../components/PageShell'
 import { AppIcon } from '../components/AppIcon'
+import { CalendarSummary } from '../components/CalendarSummary'
 import type { User, App } from '../types'
 
 export function Dashboard({ user }: { user: User }) {
@@ -30,6 +31,8 @@ export function Dashboard({ user }: { user: User }) {
           </p>
         )}
 
+        <CalendarSummary user={user} />
+
         {/* Uncategorised apps */}
         {uncategorised.length > 0 && (
           <AppGrid apps={uncategorised} onOpen={slug => navigate(`/app/${slug}`)} />