Fix missing categories and gray text in category reports

Increase category over time limit from 8 to 50 so all categories appear.
Fix category name visibility: use foreground color for bar chart Y-axis
labels and chart legend text instead of muted/inherited colors.

Closes #13

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

src/components/reports/CategoryBarChart.tsx

@@ -97,7 +97,7 @@ export default function CategoryBarChart({
               type="category"
               dataKey="category_name"
               width={120}
-              tick={{ fill: "var(--muted-foreground)", fontSize: 12 }}
+              tick={{ fill: "var(--foreground)", fontSize: 12 }}
               stroke="var(--border)"
             />
             <Tooltip

src/components/reports/CategoryOverTimeChart.tsx

@@ -134,6 +134,7 @@ export default function CategoryOverTimeChart({
               }}
               onMouseLeave={() => setHoveredCategory(null)}
               wrapperStyle={{ cursor: "pointer" }}
+              formatter={(value) => <span style={{ color: "var(--foreground)" }}>{value}</span>}
             />
             {categoryEntries.map((c) => (
               <Bar

src/services/reportService.ts

@@ -56,7 +56,7 @@ export async function getMonthlyTrends(
 export async function getCategoryOverTime(
   dateFrom?: string,
   dateTo?: string,
-  topN: number = 8,
+  topN: number = 50,
   sourceId?: number,
 ): Promise<CategoryOverTimeData> {
   const db = await getDb();