Add AST extraction tests, broader ignore patterns, build dist

- ast-extract.ts: Support tree-sitter-python and tree-sitter-go grammar
  loading (pkg.language fallback)
- discover.ts: Add cache directories to default ignore (.cache, tmp,
  temp, .turbo, .parcel-cache, .eslintcache, .prettiercache)
- tests: Add TypeScript AST extraction tests (exports + imports)
- Verified on real project: media_library_viewer (196 .pi-map.md files)
  with accurate React component extraction
- Build: npm run build produces clean dist/ output

All 16 tests pass.

tests/ast-extract.test.ts

@@ -0,0 +1,42 @@
+import { describe, it, expect } from "vitest";
+import { extractFileAST } from "../src/ast-extract.js";
+import { mkdtempSync, writeFileSync } from "fs";
+import { join } from "path";
+import { tmpdir } from "os";
+
+describe("ast-extract", () => {
+	it("extracts TypeScript exports and imports", async () => {
+		const dir = mkdtempSync(join(tmpdir(), "pi-map-ast-"));
+		const file = join(dir, "test.ts");
+		writeFileSync(
+			file,
+			`import { foo } from "./bar";
+import type { Qux } from "qux-lib";
+
+export function hello() {}
+export class MyClass {}
+export const value = 1;
+export interface Config {}
+export type MyType = string;
+export { foo as renamedFoo };
+`,
+		);
+		const result = await extractFileAST(file);
+		expect(result).not.toBeNull();
+		expect(result!.exports).toContain("hello");
+		expect(result!.exports).toContain("MyClass");
+		expect(result!.exports).toContain("value");
+		expect(result!.exports).toContain("Config");
+		expect(result!.exports).toContain("MyType");
+		expect(result!.deps).toContain("./bar");
+		expect(result!.deps).toContain("qux-lib");
+	});
+
+	it("returns null for unsupported languages", async () => {
+		const dir = mkdtempSync(join(tmpdir(), "pi-map-ast-"));
+		const file = join(dir, "test.xyz");
+		writeFileSync(file, `some content`);
+		const result = await extractFileAST(file);
+		expect(result).toBeNull();
+	});
+});