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/@aws-sdk/region-config-resolver/dist-cjs/regionConfig/stsRegionDefaultResolver.js

@@ -1,20 +0,0 @@
-"use strict";
-Object.defineProperty(exports, "__esModule", { value: true });
-exports.warning = void 0;
-exports.stsRegionDefaultResolver = stsRegionDefaultResolver;
-const config_resolver_1 = require("@smithy/config-resolver");
-const node_config_provider_1 = require("@smithy/node-config-provider");
-function stsRegionDefaultResolver(loaderConfig = {}) {
-    return (0, node_config_provider_1.loadConfig)({
-        ...config_resolver_1.NODE_REGION_CONFIG_OPTIONS,
-        async default() {
-            if (!exports.warning.silence) {
-                console.warn("@aws-sdk - WARN - default STS region of us-east-1 used. See @aws-sdk/credential-providers README and set a region explicitly.");
-            }
-            return "us-east-1";
-        },
-    }, { ...config_resolver_1.NODE_REGION_CONFIG_FILE_OPTIONS, ...loaderConfig });
-}
-exports.warning = {
-    silence: false,
-};