fix: resolve math formula display abnormal after editing report

This fix addresses the issue where math formulas become corrupted or
incorrectly displayed after editing the generated report in the editor.

**Root Cause:**
The issue occurred due to incompatibility between markdown processing
in the display component and the Tiptap editor:
1. Display component used \[\] and \(\) LaTeX delimiters
2. Tiptap Mathematics extension expects $ and 70868 delimiters
3. tiptap-markdown didn't have built-in math node serialization
4. Math syntax was lost/corrupted during editor save operations

**Solution Implemented:**
1. Created MathematicsWithMarkdown extension that adds markdown
   serialization support to Tiptap's Mathematics nodes
2. Added math delimiter normalization functions:
   - normalizeMathForEditor(): Converts LaTeX delimiters to $/70868
   - normalizeMathForDisplay(): Standardizes all delimiters to 70868
3. Updated Markdown component to use new normalization
4. Updated ReportEditor to normalize content before loading

**Changes:**
- web/src/components/editor/math-serializer.ts (new)
- web/src/components/editor/extensions.tsx
- web/src/components/editor/index.tsx
- web/src/components/deer-flow/markdown.tsx
- web/src/core/utils/markdown.ts
- web/tests/markdown-math-editor.test.ts (new)
- web/tests/markdown-katex.test.ts

**Testing:**
- Added 15 comprehensive tests for math normalization round-trip
- All tests passing (math editor + existing katex tests)
- Verified TypeScript compilation and linting

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

web/tests/markdown-katex.test.ts

@@ -3,7 +3,7 @@ import assert from "node:assert/strict";
 
 import katex from "katex";
 
-import { katexOptions } from "../src/core/markdown/katex";
+import { katexOptions } from "../src/core/markdown/katex.ts";
 
 function render(expression: string) {
   return katex.renderToString(expression, {

web/tests/markdown-math-editor.test.ts

@@ -0,0 +1,119 @@
+import { describe, it } from "node:test";
+import assert from "node:assert/strict";
+
+import { normalizeMathForEditor, normalizeMathForDisplay } from "../src/core/utils/markdown.ts";
+
+describe("markdown math normalization for editor", () => {
+  it("converts LaTeX display delimiters to $$ for editor", () => {
+    const input = "Here is a formula \\[E=mc^2\\] in the text.";
+    const output = normalizeMathForEditor(input);
+    assert.strictEqual(output, "Here is a formula $$E=mc^2$$ in the text.");
+  });
+
+  it("converts escaped LaTeX display delimiters to $$ for editor", () => {
+    const input = "Formula \\\\[x^2 + y^2 = z^2\\\\] here.";
+    const output = normalizeMathForEditor(input);
+    assert.strictEqual(output, "Formula $$x^2 + y^2 = z^2$$ here.");
+  });
+
+  it("converts LaTeX inline delimiters to $ for editor", () => {
+    const input = "Inline formula \\(a + b = c\\) in text.";
+    const output = normalizeMathForEditor(input);
+    assert.strictEqual(output, "Inline formula $a + b = c$ in text.");
+  });
+
+  it("converts escaped LaTeX inline delimiters to $ for editor", () => {
+    const input = "Inline \\\\(x = 5\\\\) here.";
+    const output = normalizeMathForEditor(input);
+    assert.strictEqual(output, "Inline $x = 5$ here.");
+  });
+
+  it("handles mixed delimiters for editor", () => {
+    const input = "Display \\[E=mc^2\\] and inline \\(F=ma\\) formulas.";
+    const output = normalizeMathForEditor(input);
+    assert.strictEqual(output, "Display $$E=mc^2$$ and inline $F=ma$ formulas.");
+  });
+
+  it("preserves already normalized math syntax for editor", () => {
+    const input = "Already normalized $$E=mc^2$$ and $F=ma$ formulas.";
+    const output = normalizeMathForEditor(input);
+    assert.strictEqual(output, "Already normalized $$E=mc^2$$ and $F=ma$ formulas.");
+  });
+});
+
+describe("markdown math normalization for display", () => {
+  it("converts LaTeX display delimiters to $$ for display", () => {
+    const input = "Here is a formula \\[E=mc^2\\] in the text.";
+    const output = normalizeMathForDisplay(input);
+    assert.strictEqual(output, "Here is a formula $$E=mc^2$$ in the text.");
+  });
+
+  it("converts escaped LaTeX display delimiters to $$ for display", () => {
+    const input = "Formula \\\\[x^2 + y^2 = z^2\\\\] here.";
+    const output = normalizeMathForDisplay(input);
+    assert.strictEqual(output, "Formula $$x^2 + y^2 = z^2$$ here.");
+  });
+
+  it("converts LaTeX inline delimiters to $$ for display", () => {
+    const input = "Inline formula \\(a + b = c\\) in text.";
+    const output = normalizeMathForDisplay(input);
+    assert.strictEqual(output, "Inline formula $$a + b = c$$ in text.");
+  });
+
+  it("converts escaped LaTeX inline delimiters to $$ for display", () => {
+    const input = "Inline \\\\(x = 5\\\\) here.";
+    const output = normalizeMathForDisplay(input);
+    assert.strictEqual(output, "Inline $$x = 5$$ here.");
+  });
+
+  it("handles mixed delimiters for display", () => {
+    const input = "Display \\[E=mc^2\\] and inline \\(F=ma\\) formulas.";
+    const output = normalizeMathForDisplay(input);
+    assert.strictEqual(output, "Display $$E=mc^2$$ and inline $$F=ma$$ formulas.");
+  });
+
+  it("handles complex physics formulas", () => {
+    const input = "Maxwell equation: \\[\\nabla \\times \\vec{E} = -\\frac{\\partial \\vec{B}}{\\partial t}\\]";
+    const output = normalizeMathForDisplay(input);
+    assert.ok(output.includes("$$"));
+    assert.ok(output.includes("nabla"));
+  });
+});
+
+describe("markdown math round-trip consistency", () => {
+  it("handles editor normalization consistently", () => {
+    const original = "Formula \\[E=mc^2\\] and \\(F=ma\\)";
+    const forEditor = normalizeMathForEditor(original);
+    
+    // Simulate editor output (should have $ and $$)
+    assert.ok(forEditor.includes("$$"));
+    assert.ok(forEditor.includes("$"));
+  });
+
+  it("handles multiple formulas correctly", () => {
+    const input = `
+# Physics Formulas
+
+Energy: \\[E = mc^2\\]
+
+Force: \\(F = ma\\)
+
+Momentum: \\[p = mv\\]
+    `;
+    
+    const forEditor = normalizeMathForEditor(input);
+    const forDisplay = normalizeMathForDisplay(input);
+    
+    // Both should have converted the delimiters
+    assert.ok(forEditor.includes("$$"));
+    assert.ok(forDisplay.includes("$$"));
+  });
+
+  it("preserves text content around formulas", () => {
+    const input = "Text before \\[E=mc^2\\] text after";
+    const output = normalizeMathForEditor(input);
+    
+    assert.ok(output.startsWith("Text before"));
+    assert.ok(output.endsWith("text after"));
+  });
+});