add .gitignore, clean up generated files from node_modules

Remove from tracking:
- dist/ (build output, regenerated by bun run build.ts)
- node_modules/.pnpm/ (pnpm internal store, 247MB)
- node_modules/.bin/ (executable symlinks)
- node_modules/.ignored/ and .ignored_* (source-map dirs moved aside by pnpm)
- 100 pnpm-installed package symlinks (regenerated by pnpm install)

Keep in tracking:
- Private package stubs not on npm (color-diff-napi, modifiers-napi,
  @ant/claude-for-chrome-mcp, @anthropic-ai/mcpb, @anthropic-ai/sandbox-runtime)
- Source-map extracted packages not installed by pnpm (@grpc/*, @protobufjs/*, etc.)

claude-code-source/node_modules/@smithy/querystring-builder/dist-cjs/index.js

@@ -1,52 +0,0 @@
-var __defProp = Object.defineProperty;
-var __getOwnPropDesc = Object.getOwnPropertyDescriptor;
-var __getOwnPropNames = Object.getOwnPropertyNames;
-var __hasOwnProp = Object.prototype.hasOwnProperty;
-var __name = (target, value) => __defProp(target, "name", { value, configurable: true });
-var __export = (target, all) => {
-  for (var name in all)
-    __defProp(target, name, { get: all[name], enumerable: true });
-};
-var __copyProps = (to, from, except, desc) => {
-  if (from && typeof from === "object" || typeof from === "function") {
-    for (let key of __getOwnPropNames(from))
-      if (!__hasOwnProp.call(to, key) && key !== except)
-        __defProp(to, key, { get: () => from[key], enumerable: !(desc = __getOwnPropDesc(from, key)) || desc.enumerable });
-  }
-  return to;
-};
-var __toCommonJS = (mod) => __copyProps(__defProp({}, "__esModule", { value: true }), mod);
-
-// src/index.ts
-var src_exports = {};
-__export(src_exports, {
-  buildQueryString: () => buildQueryString
-});
-module.exports = __toCommonJS(src_exports);
-var import_util_uri_escape = require("@smithy/util-uri-escape");
-function buildQueryString(query) {
-  const parts = [];
-  for (let key of Object.keys(query).sort()) {
-    const value = query[key];
-    key = (0, import_util_uri_escape.escapeUri)(key);
-    if (Array.isArray(value)) {
-      for (let i = 0, iLen = value.length; i < iLen; i++) {
-        parts.push(`${key}=${(0, import_util_uri_escape.escapeUri)(value[i])}`);
-      }
-    } else {
-      let qsEntry = key;
-      if (value || typeof value === "string") {
-        qsEntry += `=${(0, import_util_uri_escape.escapeUri)(value)}`;
-      }
-      parts.push(qsEntry);
-    }
-  }
-  return parts.join("&");
-}
-__name(buildQueryString, "buildQueryString");
-// Annotate the CommonJS export names for ESM import in node:
-
-0 && (module.exports = {
-  buildQueryString
-});
-