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/url-parser/dist-cjs/index.js

@@ -1,23 +0,0 @@
-'use strict';
-
-var querystringParser = require('@smithy/querystring-parser');
-
-const parseUrl = (url) => {
-    if (typeof url === "string") {
-        return parseUrl(new URL(url));
-    }
-    const { hostname, pathname, port, protocol, search } = url;
-    let query;
-    if (search) {
-        query = querystringParser.parseQueryString(search);
-    }
-    return {
-        hostname,
-        port: port ? parseInt(port) : undefined,
-        protocol,
-        path: pathname,
-        query,
-    };
-};
-
-exports.parseUrl = parseUrl;