frontend: life events + retirement goals sections on scenario detail

Two new nested CRUD sections on /scenarios/:id, each list + add form
in one card:

- Life events: name, kind (free-text with datalist suggestions —
  retirement, kid_born, mortgage_payoff, sabbatical, inheritance...),
  year_start, optional year_end (one-time vs ranged), £/year delta.
  One-line summary per row; Delete button per item.

- Goals: name, kind (target_nw, never_run_out, inheritance,
  spending_floor), comparator (>= < etc), target amount, target year,
  success threshold (probability bar). Same list+add+delete layout.

Both wire through the existing FastAPI endpoints (POST/GET on
nested paths, DELETE on flat /life-events/{id} and /goals/{id})
already shipped in Phase 0c. Mutations invalidate per-scenario
queries so the list refreshes immediately.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/pages/ScenarioDetail.tsx

@@ -10,6 +10,8 @@ import { Link, useNavigate, useParams } from 'react-router-dom';
 import { api } from '@/api/client';
 import { ApiError } from '@/api/client';
 import { FanChart } from '@/components/FanChart';
+import { GoalsSection } from '@/components/GoalsSection';
+import { LifeEventsSection } from '@/components/LifeEventsSection';
 import { gbp, pct } from '@/lib/format';
 
 export function ScenarioDetail() {
@@ -141,6 +143,9 @@ export function ScenarioDetail() {
           {String((proj.error as Error)?.message ?? proj.error)}
         </div>
       )}
+
+      <LifeEventsSection scenarioId={id} />
+      <GoalsSection scenarioId={id} />
     </section>
   );
 }