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/format.test.ts

@@ -1,5 +1,9 @@
 import { describe, it, expect } from "vitest";
-import { renderPackageMap, parsePackageMap, type PackageMapData } from "../src/format.js";
+import {
+	renderPackageMap,
+	parsePackageMap,
+	type PackageMapData,
+} from "../src/format.js";
 
 const sampleData: PackageMapData = {
 	path: "pkg/auth",
@@ -34,7 +38,9 @@ describe("format", () => {
 		expect(output).toContain("# pkg/auth");
 		expect(output).toContain("## role");
 		expect(output).toContain("## files");
-		expect(output).toContain("- tokens.ts | JWT gen/val | exp: issueToken, verifyToken, refreshToken | dep: crypto/hmac, db/sessions");
+		expect(output).toContain(
+			"- tokens.ts | JWT gen/val | exp: issueToken, verifyToken, refreshToken | dep: crypto/hmac, db/sessions",
+		);
 		expect(output).toContain("## arch");
 		expect(output).toContain("## dirty");
 		expect(output).toContain("-");
@@ -53,7 +59,11 @@ describe("format", () => {
 		const tokens = parsed.files.find((f) => f.name === "tokens.ts");
 		expect(tokens).toBeDefined();
 		expect(tokens!.purpose).toBe("JWT gen/val");
-		expect(tokens!.exports).toEqual(["issueToken", "verifyToken", "refreshToken"]);
+		expect(tokens!.exports).toEqual([
+			"issueToken",
+			"verifyToken",
+			"refreshToken",
+		]);
 		expect(tokens!.deps).toEqual(["crypto/hmac", "db/sessions"]);
 	});
 
@@ -61,7 +71,9 @@ describe("format", () => {
 		const data: PackageMapData = {
 			path: "pkg/utils",
 			role: "Utilities",
-			files: [{ name: "helpers.ts", purpose: "Helpers", exports: [], deps: [] }],
+			files: [
+				{ name: "helpers.ts", purpose: "Helpers", exports: [], deps: [] },
+			],
 			arch: "Shared helpers",
 			dirty: "2024-01-01: patched",
 		};