feat(phases-10-15): complete TapTrack Hub v1.0

Phase 10 — Support Ticket System:
- tickets.py router: SLA status (on_track/at_risk/breached/responded), email
  notifications on create+reply via background threads, school_name in list,
  priority filter, bulk-close endpoint
- tasks/tickets.py: escalate_stale Celery task (48h→high, 72h no reply→urgent)
- worker.py: escalate_stale scheduled every hour
- templates/email/ticket_notification.html: HTML ticket notification email
- TicketsPage.vue: status tabs, SLA badge, priority badge, school name column,
  checkbox bulk-close, pagination
- TicketDetailPage.vue: inline priority/status/assignee selectors, SLA timer,
  internal note lock icon, closed-ticket guard

Phase 11 — Monthly Report Generation:
- models/report.py: MonthlyReport + SchoolMonthlyStats ORM models
- tasks/reports.py: send_monthly_reports enhanced with SMS stats, attendance
  data, invoice summary, stores MonthlyReport record per school per month

Phase 12 — On-Prem Monthly Report Pull:
- tasks/reports.py: pull_monthly_stats task — httpx GET to each school's
  hub_base_url, upserts SchoolMonthlyStats; runs 1st at 5am
- worker.py: pull_monthly_stats scheduled 1st at 5am

Phase 13 — Feature Flags + Suspension:
- models/school.py: hub_base_url, feature_overrides (JSON), onboarding_completed_at
- routers/schools.py: PUT /{id}/feature-overrides endpoint
- routers/sync.py: _tier_features() merges school.feature_overrides into poll config

Phase 14 — Onboarding Wizard + Welcome Email:
- tasks/onboarding.py: send_welcome_email Celery task with license key
- routers/schools.py: auto-trigger welcome email on POST /schools,
  POST /{id}/activate (status→active + onboarding_completed_at),
  POST /{id}/resend-welcome

Phase 15 — UX Polish + Ops Tools:
- routers/search.py: GET /api/search?q= (schools + invoices + tickets, 5 each)
- routers/audit.py: GET /api/audit-logs (paginated, filterable)
- AppLayout.vue: global search bar with debounced dropdown, result navigation
- AuditLogsPage.vue: new page with filter + pagination
- AppSidebar.vue: Audit Logs nav item added
- router/index.ts: /audit-logs route
- api.ts: globalSearch, getAuditLogs, activateSchool, resendWelcomeEmail,
  updateFeatureOverrides, bulkCloseTickets

Deployment:
- docker-compose.yml: x-backend-env anchor (DRY), PDF_DIR env var,
  seed service (one-shot python seed.py on first boot)
- migrations/003_phases11_15.py: monthly_reports, school_monthly_stats tables
  + schools hub_base_url/feature_overrides/onboarding_completed_at columns

backend/app/templates/email/ticket_notification.html

@@ -0,0 +1,22 @@
+{% extends "email/base.html" %}
+{% block content %}
+<h2>{{ email_title }}</h2>
+<p>Dear {{ recipient_name }},</p>
+
+<div class="info-box">
+  <div class="row"><span class="label">Ticket</span><span class="value">{{ ticket_number }}</span></div>
+  <div class="row"><span class="label">Subject</span><span class="value">{{ subject }}</span></div>
+  <div class="row"><span class="label">Category</span><span class="value" style="text-transform:capitalize">{{ category }}</span></div>
+  <div class="row"><span class="label">Priority</span><span class="value" style="text-transform:capitalize">{{ priority }}</span></div>
+  <div class="row"><span class="label">Status</span><span class="value" style="text-transform:capitalize">{{ status }}</span></div>
+</div>
+
+<div style="background:#f8fafc;border:1px solid #e2e8f0;border-radius:8px;padding:16px;margin:16px 0">
+  <p style="font-size:11px;color:#94a3b8;margin:0 0 8px;font-weight:600;text-transform:uppercase;letter-spacing:0.5px">{{ message_label }}</p>
+  <p style="margin:0;white-space:pre-wrap;color:#334155">{{ message_body }}</p>
+</div>
+
+<p><a class="btn" href="{{ ticket_url }}">View Ticket</a></p>
+
+<p>Thank you,<br><strong>TapTrack Hub Team</strong></p>
+{% endblock %}