Improve monthly insights: structured prompt, bullet recommendations, visual cards

- Strengthen prompt with required observations (savings rate, spend-to-income,
  top category, anomaly), dollar-formatted amounts, and pay schedule context
- Preserve recommendation array structure; store as JSON array string in DB
- Render recommendations as numbered cards with icons in home dashboard
- Add spend-vs-income progress bar and category flow mini bar chart
- Fix test assertions for new JSON array recommendation format

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

src/lib/insights.test.ts

@@ -18,6 +18,7 @@ vi.mock("@/lib/db", () => {
     db: {
       expense: { findMany: vi.fn() },
       paycheck: { findMany: vi.fn() },
+      paySchedule: { findFirst: vi.fn().mockResolvedValue(null) },
       monthlyInsight,
     },
   };
@@ -86,7 +87,7 @@ describe("generateMonthlyInsight", () => {
 
     expect(result.source).toBe("model");
     expect(result.insight.summary).toBe("Spending is stable.");
-    expect(result.insight.recommendations).toBe("Keep food spending under watch.");
+    expect(result.insight.recommendations).toBe('["Keep food spending under watch."]');
   });
 
   it("coerces array recommendations from the local model", async () => {