perf: Performance optimalisaties (4 iteraties)

Iteratie 1 - Parallel Fetching:
- Patient dashboard: Promise.all voor 3 data fetches
- Resultaat: ~45% sneller (800ms → 440ms)

Iteratie 2 - Loading States:
- Skeleton loaders voor EPD, patient, agenda, rapportage
- Betere perceived performance tijdens laden

Iteratie 3 - Lazy Load FullCalendar:
- Dynamic import met next/dynamic (ssr: false)
- ~150KB minder in initiële bundle

Iteratie 4 - Reports API Optimalisatie:
- Selectieve kolommen (10 i.p.v. 20)
- Server-side pagination (limit/offset)
- Database indexes voor timeline queries
- Resultaat: 89% sneller (1671ms → 188ms)

Overige fixes:
- Type casts voor Json → Behandelstructuur/SmartGoal/etc.
- Metadata template fix in layout.tsx

Documentatie:
- docs/audit-rapport.md - PO-vriendelijk audit rapport
- docs/performance/baseline-2025-12-12.md - Metingen + resultaten

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

supabase/migrations/20251212_add_reports_timeline_index.sql

@@ -0,0 +1,19 @@
+-- Add optimized index for reports timeline queries
+-- This covering index speeds up the most common query pattern:
+-- SELECT id, type, content, shift_date, ... FROM reports
+-- WHERE patient_id = ? AND deleted_at IS NULL
+-- ORDER BY created_at DESC
+
+-- Composite index for timeline queries with included columns
+CREATE INDEX IF NOT EXISTS idx_reports_timeline
+  ON reports(patient_id, created_at DESC)
+  WHERE deleted_at IS NULL;
+
+-- Index for type filtering (used when filtering by report types)
+CREATE INDEX IF NOT EXISTS idx_reports_patient_type
+  ON reports(patient_id, type)
+  WHERE deleted_at IS NULL;
+
+-- Note: PostgreSQL doesn't support INCLUDE clause in partial indexes,
+-- so we use a standard composite index. The query planner will use
+-- these indexes for the filtered queries.