feat: M7 proper LLM integration with dual providers, caching, and parallel batching

- Add LLM client abstraction (src/llm-client.ts) with factory pattern
- Add OpenAI-compatible external client (src/external-llm-client.ts)
- Add Kimi.com client using Anthropic-based API (src/kimi-llm-client.ts)
- Add Pi native LLM stub (src/pi-llm-client.ts) for future ExtensionAPI wiring
- Add SHA-256 disk cache at ~/.cache/pi-project-map/ (src/llm-cache.ts)
- Add parallel batching with p-limit, retry + exponential backoff (src/llm-batch.ts)
- Rewrite llm-extract.ts to use real LLM calls with structured prompts
  - File-level: PURPOSE, DEPS, CONCEPTS
  - Package-level: ROLE, ARCH
  - Context truncation, 50KB skip, cache before LLM call
- Wire CLI with --llm-provider, --llm-model, --llm-base-url flags
- Update config.ts with llmProvider, llmBaseUrl fields
- Update init.ts and patch.ts to accept optional LLMClient
- Add sample project fixture for manual testing
- Add tests: llm-cache (3), llm-batch (5), llm-integration (8 with real Kimi API),
  pi-extension (14 mocked)
- All 56 tests pass

fixtures/sample-project/src/components/Button.tsx

@@ -0,0 +1,27 @@
+import React from "react";
+
+export interface ButtonProps {
+  label: string;
+  variant?: "primary" | "secondary" | "danger";
+  onClick?: () => void;
+  disabled?: boolean;
+}
+
+export function Button({
+  label,
+  variant = "primary",
+  onClick,
+  disabled = false,
+}: ButtonProps): JSX.Element {
+  return (
+    <button
+      className={`btn btn--${variant}`}
+      onClick={onClick}
+      disabled={disabled}
+    >
+      {label}
+    </button>
+  );
+}
+
+export default Button;

fixtures/sample-project/src/components/UserCard.tsx

@@ -0,0 +1,23 @@
+import React from "react";
+import type { User } from "../models/user.js";
+
+export interface UserCardProps {
+  user: User;
+  onEdit?: (user: User) => void;
+  onDelete?: (id: string) => void;
+}
+
+export function UserCard({ user, onEdit, onDelete }: UserCardProps): JSX.Element {
+  return (
+    <div className="user-card">
+      <h3>{user.name}</h3>
+      <p>{user.email}</p>
+      <div className="actions">
+        {onEdit && <button onClick={() => onEdit(user)}>Edit</button>}
+        {onDelete && <button onClick={() => onDelete(user.id)}>Delete</button>}
+      </div>
+    </div>
+  );
+}
+
+export default UserCard;

fixtures/sample-project/src/index.ts

@@ -0,0 +1,14 @@
+import { createUser } from "./models/user.js";
+import { validateEmail } from "./utils/validation.js";
+import { logger } from "./utils/logger.js";
+
+export async function main() {
+  const user = createUser({ email: "test@example.com", name: "Alice" });
+  if (!validateEmail(user.email)) {
+    logger.error("Invalid email");
+    return;
+  }
+  logger.info(`User created: ${user.name}`);
+}
+
+export { createUser, validateEmail, logger };

fixtures/sample-project/src/models/user.ts

@@ -0,0 +1,23 @@
+import { validateEmail } from "../utils/validation.js";
+
+export interface User {
+  id: string;
+  email: string;
+  name: string;
+  createdAt: Date;
+}
+
+export function createUser(data: Omit<User, "id" | "createdAt">): User {
+  if (!validateEmail(data.email)) {
+    throw new Error("Invalid email");
+  }
+  return {
+    id: crypto.randomUUID(),
+    ...data,
+    createdAt: new Date(),
+  };
+}
+
+export function serializeUser(user: User): string {
+  return JSON.stringify(user);
+}

fixtures/sample-project/src/utils/logger.ts

@@ -0,0 +1,22 @@
+export type LogLevel = "debug" | "info" | "warn" | "error";
+
+export function log(level: LogLevel, message: string): void {
+  const timestamp = new Date().toISOString();
+  console.log(`[${timestamp}] ${level.toUpperCase()}: ${message}`);
+}
+
+export function debug(message: string): void {
+  log("debug", message);
+}
+
+export function info(message: string): void {
+  log("info", message);
+}
+
+export function warn(message: string): void {
+  log("warn", message);
+}
+
+export function error(message: string): void {
+  log("error", message);
+}

fixtures/sample-project/src/utils/validation.ts

@@ -0,0 +1,13 @@
+const EMAIL_REGEX = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
+
+export function validateEmail(email: string): boolean {
+  return EMAIL_REGEX.test(email);
+}
+
+export function validateNotEmpty(value: string): boolean {
+  return value.trim().length > 0;
+}
+
+export function validateMinLength(value: string, min: number): boolean {
+  return value.length >= min;
+}