Fix discover, improve LLM heuristics, add integration tests

- discover.ts: Fix ignore package path handling for root '.' directories,
  add .pi-map.md to default ignore list
- llm-extract.ts: Fix export regex to only match line-start exports and
  handle 'export async function', fix root package role to 'Project root'
- init.ts: Minor cleanup
- .gitignore: Add .pi-map.md
- tests: 6 integration tests covering init, patch (small/large packages),
  validate (missing, orphaned, stale-signature detection)

All 14 tests pass. TypeScript compiles clean.

tests/integration.test.ts

@@ -0,0 +1,119 @@
+import { describe, it, expect, beforeEach, afterEach } from "vitest";
+import { mkdtempSync, writeFileSync, mkdirSync, rmSync, readFileSync } from "fs";
+import { join } from "path";
+import { tmpdir } from "os";
+import { initProject } from "../src/init.js";
+import { patchFile } from "../src/patch.js";
+import { validateMaps } from "../src/validate.js";
+
+describe("integration", () => {
+	let dir: string;
+
+	beforeEach(() => {
+		dir = mkdtempSync(join(tmpdir(), "pi-map-int-"));
+	});
+
+	afterEach(() => {
+		rmSync(dir, { recursive: true });
+	});
+
+	it("init creates .pi-map.md files", async () => {
+		mkdirSync(join(dir, "src"));
+		writeFileSync(
+			join(dir, "src", "index.ts"),
+			`export function foo() {}\n`,
+		);
+		await initProject(dir);
+
+		const map = readFileSync(join(dir, "src", ".pi-map.md"), "utf8");
+		expect(map).toContain("# src");
+		expect(map).toContain("foo");
+	});
+
+	it("patch updates a file entry", async () => {
+		mkdirSync(join(dir, "src"));
+		writeFileSync(
+			join(dir, "src", "index.ts"),
+			`export function foo() {}\n`,
+		);
+		writeFileSync(
+			join(dir, "src", "utils.ts"),
+			`export const bar = 1;\n`,
+		);
+		await initProject(dir);
+
+		// Modify a file
+		writeFileSync(
+			join(dir, "src", "index.ts"),
+			`export function foo() {}\nexport function baz() {}\n`,
+		);
+		await patchFile(join(dir, "src", "index.ts"));
+
+		const map = readFileSync(join(dir, "src", ".pi-map.md"), "utf8");
+		expect(map).toContain("baz");
+	});
+
+	it("patch adds dirty marker for large packages", async () => {
+		mkdirSync(join(dir, "src"));
+		// Create 11 files so it's a "large" package
+		for (let i = 0; i < 11; i++) {
+			writeFileSync(
+				join(dir, "src", `file${i}.ts`),
+				`export const x${i} = ${i};\n`,
+			);
+		}
+		await initProject(dir);
+
+		// Modify a file
+		writeFileSync(
+			join(dir, "src", "file0.ts"),
+			`export const x0 = 0;\nexport const y = 99;\n`,
+		);
+		await patchFile(join(dir, "src", "file0.ts"));
+
+		const map = readFileSync(join(dir, "src", ".pi-map.md"), "utf8");
+		expect(map).toContain("y");
+		expect(map).toContain("dirty");
+		expect(map).toContain("patched");
+	});
+
+	it("validate detects new files", async () => {
+		mkdirSync(join(dir, "src"));
+		writeFileSync(join(dir, "src", "a.ts"), `export const a = 1;\n`);
+		await initProject(dir);
+
+		// Add new file
+		writeFileSync(join(dir, "src", "b.ts"), `export const b = 2;\n`);
+
+		const result = await validateMaps(dir);
+		expect(result.clean).toBe(false);
+		expect(result.discrepancies.some((d) => d.type === "missing")).toBe(true);
+	});
+
+	it("validate detects deleted files", async () => {
+		mkdirSync(join(dir, "src"));
+		writeFileSync(join(dir, "src", "a.ts"), `export const a = 1;\n`);
+		writeFileSync(join(dir, "src", "b.ts"), `export const b = 2;\n`);
+		await initProject(dir);
+
+		// Delete a file
+		rmSync(join(dir, "src", "b.ts"));
+
+		const result = await validateMaps(dir);
+		expect(result.clean).toBe(false);
+		expect(result.discrepancies.some((d) => d.type === "orphaned")).toBe(true);
+	});
+
+	it("validate detects changed signatures", async () => {
+		mkdirSync(join(dir, "src"));
+		writeFileSync(join(dir, "src", "a.ts"), `export const a = 1;\n`);
+		await initProject(dir);
+
+		// Change exports
+		writeFileSync(join(dir, "src", "a.ts"), `export const a = 1;\nexport const c = 3;\n`);
+
+		const result = await validateMaps(dir);
+		expect(result.clean).toBe(false);
+		expect(result.discrepancies.some((d) => d.type === "stale-signature")).toBe(true);
+	});
+});