feat(phase-7): complete school admin portal UI

Backend (school_portal.py):
- GET /portal/sms-stats: 30/7/90-day chart, delivery rate, credit burn this month
- POST /portal/credits/request: auto-creates billing ticket for credit top-up
- GET /portal/overview: extended with days_left, sms_credit_low flag, 30-day SMS chart, full school details

PortalOverviewPage: suspension/expired banner, low-credit warning, credit meter
  with progress bar, license countdown with expiry badge, 30-day SMS sparkline
PortalBillingPage: subscription plan panel (fee, SMS cost, cycle, next billing),
  invoice table with subscription/SMS breakdown, credit top-up request form
PortalSmsPage: 30/7/90d period picker, 4-stat KPI row (sent, failed, delivery
  rate, credit burn), daily volume chart, credit snapshot with top-up link,
  paginated SMS log with status filter
PortalTicketsPage: status filter tabs (all/open/in-progress/resolved/closed),
  pagination, improved empty states
PortalProfilePage: school details panel (name, city, contact, tier, status)
  alongside existing change-password form

.paul/ROADMAP.md

@@ -19,8 +19,8 @@ SMS flow: On-prem TapTrack polls Hub every 30s → Hub queues SMS jobs → Hub s
 ## Current Milestone
 
 **v1.0 — Foundation & Core Services**
-Status: Phase 6 complete — Phase 7 next
-Phases: 6 of 15 complete
+Status: Phase 7 complete — Phase 8 next
+Phases: 7 of 15 complete
 
 ---
 
@@ -34,7 +34,7 @@ Phases: 6 of 15 complete
 | 4     | SMS Gateway (credits + queue)  | 2   | ✅ Complete  | 2026-03-15 |
 | 5     | On-Prem SMS Polling Agent      | 1   | ✅ Complete  | 2026-03-16 |
 | 6     | Super Admin Dashboard UI       | 1   | ✅ Complete  | 2026-03-16 |
-| 7     | School Admin Portal UI         | TBD | Not started  | —          |
+| 7     | School Admin Portal UI         | 1   | ✅ Complete  | 2026-03-16 |
 | 8     | Billing Engine + Invoice PDF   | TBD | Not started  | —          |
 | 9     | Email Dispatcher               | TBD | Not started  | —          |
 | 10    | Support Ticket System          | TBD | Not started  | —          |