fix: disable single-dollar math to prevent currency symbol text corruption

Set singleDollarTextMath: false in remarkMath config so that single $
signs (e.g. R$, US$, $100) are not treated as inline math delimiters.
Math expressions still work with $$ syntax.

Fixes #11648

webview-ui/src/components/common/MarkdownBlock.tsx

@@ -308,7 +308,7 @@ const MarkdownBlock = memo(({ markdown }: MarkdownBlockProps) => {
 			<ReactMarkdown
 				remarkPlugins={[
 					remarkGfm,
-					remarkMath,
+					[remarkMath, { singleDollarTextMath: false }],
 					() => {
 						return (tree: any) => {
 							visit(tree, "code", (node: any) => {

webview-ui/src/components/common/__tests__/MarkdownBlock.spec.tsx

@@ -88,6 +88,46 @@ describe("MarkdownBlock", () => {
 		expect(screen.getByText("Step three")).toBeInTheDocument()
 	})
 
+	it("should render currency symbols without text corruption", async () => {
+		const markdown = "The price is R$100 or US$50."
+		const { container } = render(<MarkdownBlock markdown={markdown} />)
+
+		await screen.findByText(/The price is/, { exact: false })
+
+		const paragraph = container.querySelector("p")
+		expect(paragraph?.textContent).toBe("The price is R$100 or US$50.")
+
+		// Should not produce any math/katex elements
+		const mathElements = container.querySelectorAll(".katex")
+		expect(mathElements.length).toBe(0)
+	})
+
+	it("should render double-dollar math expressions", async () => {
+		const markdown = "The formula is $$x^2 + y^2 = z^2$$."
+		const { container } = render(<MarkdownBlock markdown={markdown} />)
+
+		await screen.findByText(/The formula is/, { exact: false })
+
+		// Should render katex math
+		const mathElements = container.querySelectorAll(".katex")
+		expect(mathElements.length).toBeGreaterThan(0)
+	})
+
+	it("should not treat single dollar signs as math delimiters", async () => {
+		const markdown = "Cost: $50 to $100 range."
+		const { container } = render(<MarkdownBlock markdown={markdown} />)
+
+		await screen.findByText(/Cost/, { exact: false })
+
+		const paragraph = container.querySelector("p")
+		expect(paragraph?.textContent).toContain("$50")
+		expect(paragraph?.textContent).toContain("$100")
+
+		// No math elements should be created from single-dollar text
+		const mathElements = container.querySelectorAll(".katex")
+		expect(mathElements.length).toBe(0)
+	})
+
 	it("should render nested lists with proper hierarchy", async () => {
 		const markdown = `Complex list:
 1. First level ordered