feat(05-01): edit design tokens and add CSS overrides in index.css

- Set --radius: 0 for sharp-cornered design system cascade
- Warm background chroma from 0.005 to 0.01
- Delete --color-chart-1 through --color-chart-5 (redundant with fill vars)
- Raise fill chroma to 0.22+ for vibrant pastel category colors
- Add .recharts-rectangle and [data-sonner-toast] radius overrides

src/index.css

@@ -4,7 +4,7 @@
 
 @theme inline {
   /* Pastel OKLCH Color System */
-  --color-background: oklch(0.98 0.005 260);
+  --color-background: oklch(0.98 0.01 260);
   --color-foreground: oklch(0.25 0.02 260);
 
   --color-card: oklch(1 0 0);
@@ -49,27 +49,20 @@
   --color-saving: oklch(0.55 0.16 220);
   --color-investment: oklch(0.55 0.16 285);
 
-  /* Chart Colors */
-  --color-chart-1: oklch(0.72 0.14 155);
-  --color-chart-2: oklch(0.7 0.14 25);
-  --color-chart-3: oklch(0.72 0.14 50);
-  --color-chart-4: oklch(0.65 0.16 355);
-  --color-chart-5: oklch(0.72 0.14 220);
-
   /* Semantic Status Tokens */
   --color-over-budget: oklch(0.55 0.20 25);
   --color-on-budget: oklch(0.50 0.17 155);
   --color-budget-bar-bg: oklch(0.92 0.01 260);
 
   /* Chart Fill Variants */
-  --color-income-fill: oklch(0.68 0.19 155);
-  --color-bill-fill: oklch(0.65 0.19 25);
-  --color-variable-expense-fill: oklch(0.70 0.18 50);
-  --color-debt-fill: oklch(0.60 0.20 355);
-  --color-saving-fill: oklch(0.68 0.18 220);
-  --color-investment-fill: oklch(0.65 0.18 285);
+  --color-income-fill: oklch(0.72 0.22 155);
+  --color-bill-fill: oklch(0.70 0.22 25);
+  --color-variable-expense-fill: oklch(0.74 0.22 50);
+  --color-debt-fill: oklch(0.66 0.23 355);
+  --color-saving-fill: oklch(0.72 0.22 220);
+  --color-investment-fill: oklch(0.68 0.22 285);
 
-  --radius: 0.625rem;
+  --radius: 0;
 
   /* Collapsible animation */
   --animate-collapsible-open: collapsible-open 200ms ease-out;
@@ -97,3 +90,13 @@
     font-feature-settings: "rlig" 1, "calt" 1;
   }
 }
+
+/* Third-party radius overrides */
+.recharts-rectangle {
+  rx: 0;
+  ry: 0;
+}
+
+[data-sonner-toast] {
+  border-radius: 0 !important;
+}