feat: proper time-based X-axis with angled hour labels and bold dates

Replaced string-based X-axis with numeric timestamp axis:
- Custom ChartXTick component renders hour marks at -35° angle
- New day boundaries shown in bold (e.g., 'Apr 29')
- Hour marks shown as '9:00 AM', '10:00 AM' etc.
- Tooltip shows full date+time on hover
- Direction timeline uses formatted timestamps
- Bottom margin increased to accommodate angled labels

frontend/src/pages/CompanyDetail.tsx

@@ -602,13 +602,46 @@ interface ChartPoint {
   price?: number;
 }
 
+function ChartXTick({ x, y, payload }: { x?: number; y?: number; payload?: { value: number } }) {
+  if (!payload || !x || !y) return null;
+  const d = new Date(payload.value);
+  const hour = d.getHours();
+  const minute = d.getMinutes();
+  const isNewDay = hour === 0 && minute < 30;
+  const isHourMark = minute < 15; // Show only on-the-hour ticks
+
+  // For date labels (new day boundary)
+  if (isNewDay) {
+    const label = d.toLocaleDateString('en-US', { month: 'short', day: 'numeric' });
+    return (
+      <g transform={`translate(${x},${y})`}>
+        <text x={0} y={12} textAnchor="middle" fill="#e2e8f0" fontSize={11} fontWeight="bold">
+          {label}
+        </text>
+      </g>
+    );
+  }
+
+  // For time labels — show rounded hours at an angle
+  if (!isHourMark) return null;
+  const timeStr = d.toLocaleTimeString('en-US', { hour: 'numeric', minute: '2-digit' });
+  return (
+    <g transform={`translate(${x},${y})`}>
+      <text x={0} y={8} textAnchor="end" fill="#94a3b8" fontSize={10} transform="rotate(-35)">
+        {timeStr}
+      </text>
+    </g>
+  );
+}
+
 function TrendTooltip({ active, payload, label }: Record<string, unknown>) {
   if (!active) return null;
   const items = payload as Array<{ name: string; value: number; color: string; dataKey: string }> | undefined;
   if (!items?.length) return null;
+  const ts = typeof label === 'number' ? new Date(label).toLocaleString('en-US', { month: 'short', day: 'numeric', hour: 'numeric', minute: '2-digit' }) : String(label ?? '');
   return (
     <div className="rounded-lg border border-surface-700 bg-surface-900 px-3 py-2 text-xs shadow-lg">
-      <div className="mb-1 text-gray-400">{String(label ?? '')}</div>
+      <div className="mb-1 text-gray-400">{ts}</div>
       {items.map((item, i) => (
         <div key={i} className="flex justify-between gap-4" style={{ color: item.color }}>
           <span>{item.name}:</span>
@@ -709,7 +742,7 @@ function TrendHistoryChart({ trends, latestTrends, ticker, marketPrices, selecte
     const trendTs = new Date(t.generated_at).getTime();
     const price = findClosestPrice(trendTs);
     return {
-      time: new Date(t.generated_at).toLocaleDateString('en-US', { month: 'short', day: 'numeric', hour: '2-digit', minute: '2-digit' }),
+      time: String(trendTs),
       timestamp: trendTs,
       strength: +(t.trend_strength * 100).toFixed(1),
       confidence: +(t.confidence * 100).toFixed(1),
@@ -766,12 +799,16 @@ function TrendHistoryChart({ trends, latestTrends, ticker, marketPrices, selecte
               Trend Strength & Confidence — {ticker} / {selectedWindow}
             </h2>
             <ResponsiveContainer width="100%" height={280}>
-              <LineChart data={chartData} margin={{ top: 5, right: 20, bottom: 5, left: 0 }}>
+              <LineChart data={chartData} margin={{ top: 5, right: 20, bottom: 40, left: 0 }}>
                 <CartesianGrid strokeDasharray="3 3" stroke="#334155" />
                 <XAxis
-                  dataKey="time"
-                  tick={{ fill: '#94a3b8', fontSize: 11 }}
+                  dataKey="timestamp"
+                  type="number"
+                  domain={['dataMin', 'dataMax']}
+                  scale="time"
+                  tick={<ChartXTick />}
                   tickLine={{ stroke: '#475569' }}
+                  interval="preserveStartEnd"
                 />
                 <YAxis
                   yAxisId="left"
@@ -853,13 +890,13 @@ function TrendHistoryChart({ trends, latestTrends, ticker, marketPrices, selecte
                   'bg-gray-600';
                 const height = Math.max(8, pt.strength * 0.5);
                 return (
-                  <div key={i} className="flex flex-col items-center gap-1" title={`${pt.time}: ${pt.directionLabel} (${pt.strength}%)`}>
+                  <div key={i} className="flex flex-col items-center gap-1" title={`${new Date(pt.timestamp).toLocaleString('en-US', { month: 'short', day: 'numeric', hour: 'numeric', minute: '2-digit' })}: ${pt.directionLabel} (${pt.strength}%)`}>
                     <div
                       className={`w-3 rounded-sm ${color}`}
                       style={{ height: `${height}px` }}
                     />
                     {i % Math.max(1, Math.floor(chartData.length / 8)) === 0 && (
-                      <span className="text-[9px] text-gray-500 -rotate-45 origin-top-left whitespace-nowrap">{pt.time}</span>
+                      <span className="text-[9px] text-gray-500 -rotate-45 origin-top-left whitespace-nowrap">{new Date(pt.timestamp).toLocaleTimeString('en-US', { hour: 'numeric', minute: '2-digit' })}</span>
                     )}
                   </div>
                 );