fix: restyle sankey to match reference - thinner nodes, all labels, scrollable

- Switch to fixed-width Sankey with horizontal scroll (250px per step)
- Thinner nodes (8px), tighter spacing (8px)
- Labels on all columns, not just first/last
- Lower link opacity (0.15) for cleaner look
- Increased node cap to 25 per step

components/journeys/SankeyJourney.tsx

@@ -1,7 +1,7 @@
 'use client'
 
 import { useCallback, useEffect, useMemo, useState } from 'react'
-import { ResponsiveSankey } from '@nivo/sankey'
+import { Sankey } from '@nivo/sankey'
 import { TreeStructure, X } from '@phosphor-icons/react'
 import type { PathTransition } from '@/lib/api/journeys'
 
@@ -36,7 +36,7 @@ const COLUMN_COLORS = [
   '#EC4899', '#06B6D4', '#EF4444', '#84CC16', '#F97316', '#6366F1',
 ]
 
-const MAX_NODES_PER_STEP = 15
+const MAX_NODES_PER_STEP = 25
 
 // ─── Helpers ────────────────────────────────────────────────────────
 
@@ -257,9 +257,11 @@ export default function SankeyJourney({
   }
 
   const labelColor = isDark ? '#a3a3a3' : '#525252'
-  const steps = data.nodes.map((n) => n.stepIndex)
-  const minStep = Math.min(...steps)
-  const maxStep = Math.max(...steps)
+
+  // Calculate dimensions: give each step ~250px of horizontal space
+  const numSteps = new Set(data.nodes.map((n) => n.stepIndex)).size
+  const chartWidth = Math.max(800, numSteps * 250)
+  const chartHeight = 500
 
   return (
     <div>
@@ -283,38 +285,35 @@ export default function SankeyJourney({
         </div>
       )}
 
-      <div style={{ height: 500 }}>
-        <ResponsiveSankey<SankeyNode, SankeyLink>
+      <div className="overflow-x-auto -mx-6 px-6" style={{ maxHeight: chartHeight + 16 }}>
+        <div style={{ width: chartWidth, height: chartHeight }}>
+          <Sankey<SankeyNode, SankeyLink>
             data={data}
-          margin={{ top: 8, right: 140, bottom: 8, left: 140 }}
+            width={chartWidth}
+            height={chartHeight}
+            margin={{ top: 8, right: 160, bottom: 8, left: 160 }}
             align="justify"
             sort="descending"
             colors={(node) =>
               COLUMN_COLORS[node.stepIndex % COLUMN_COLORS.length]
             }
-          nodeThickness={12}
-          nodeSpacing={20}
+            nodeThickness={8}
+            nodeSpacing={8}
             nodeInnerPadding={0}
             nodeBorderWidth={0}
-          nodeBorderRadius={3}
+            nodeBorderRadius={2}
             nodeOpacity={1}
             nodeHoverOpacity={1}
             nodeHoverOthersOpacity={0.3}
-          linkOpacity={0.2}
+            linkOpacity={0.15}
             linkHoverOpacity={0.5}
-          linkHoverOthersOpacity={0.05}
-          linkContract={2}
+            linkHoverOthersOpacity={0.03}
+            linkContract={1}
             enableLinkGradient
             enableLabels
-          label={(node) => {
-            // Only show labels for first and last step columns
-            if (node.stepIndex === minStep || node.stepIndex === maxStep) {
-              return smartLabel(pathFromId(node.id))
-            }
-            return ''
-          }}
+            label={(node) => smartLabel(pathFromId(node.id))}
             labelPosition="outside"
-          labelPadding={8}
+            labelPadding={6}
             labelTextColor={labelColor}
             isInteractive
             onClick={handleClick}
@@ -352,5 +351,6 @@ export default function SankeyJourney({
           />
         </div>
       </div>
+    </div>
   )
 }