feat(sprint-5/etapa-3): heatmap gradiente 4 stops + modo percentil + localStorage + fix zoom

- colors.ts: gradiente continuo verde→amarillo→naranja→rojo (interpolación N-stops genérica)
- Renombra modos: relative→percentile (rank-based), absolute→minmax
- Hook useHeatmapMode(): persiste selección en localStorage con clave inq-roi:heatmap-mode
- HeatmapLegend: barra de 4 stops, labels P0/P50/P100 en modo percentil
- HeatmapModeToggle: etiquetas "Percentil" / "Min-max"
- pdf-sections.ts: leyenda PDF con 4 stops interpolados
- BpmnCanvas: controles de zoom movidos a esquina inferior izquierda (evita logo bpmn.io)
- Tests: 528 unitarios pasan; E2E recalibrados con vecino más cercano (distancia euclidiana)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/features/report/derivations.test.ts

@@ -213,7 +213,7 @@ describe('buildTopActivitiesOption — estructura', () => {
   it('serie de tipo bar con hasta 10 items', () => {
     const xml = loadBpmn('medium-with-gateways.bpmn')
     const result = runSimulation(buildSimInput(xml, 100, 0.2))
-    const option = buildTopActivitiesOption(result.perActivity, 'relative', 'USD')
+    const option = buildTopActivitiesOption(result.perActivity, 'percentile', 'USD')
     const series = option.series as any[]
     expect(series[0].type).toBe('bar')
     expect(series[0].data.length).toBeLessThanOrEqual(10)
@@ -225,7 +225,7 @@ describe('buildTopActivitiesOption — estructura', () => {
     const result = runSimulation(buildSimInput(xml, 200, 0))
     // En modo relativo con varianza real, la 1ra actividad → t=1 → rojo
     // En simple-linear todos cuestan igual → NEUTRAL_HEATMAP_COLOR
-    const option = buildTopActivitiesOption(result.perActivity, 'relative', 'USD')
+    const option = buildTopActivitiesOption(result.perActivity, 'percentile', 'USD')
     const series = option.series as any[]
     // Verifica que itemStyle.color existe en cada barra
     series[0].data.forEach((item: any) => {
@@ -237,7 +237,7 @@ describe('buildTopActivitiesOption — estructura', () => {
   it('yAxis data contiene los nombres de actividades (truncados)', () => {
     const xml = loadBpmn('simple-linear.bpmn')
     const result = runSimulation(buildSimInput(xml, 100, 0))
-    const option = buildTopActivitiesOption(result.perActivity, 'relative', 'USD')
+    const option = buildTopActivitiesOption(result.perActivity, 'percentile', 'USD')
     const yAxis = option.yAxis as any
     expect(yAxis.data).toHaveLength(result.perActivity.length)
     // Los nombres deben existir (no vacíos)