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/@anthropic-ai/bedrock-sdk/internal/utils/env.mjs

@@ -1,18 +0,0 @@
-// File generated from our OpenAPI spec by Stainless. See CONTRIBUTING.md for details.
-/**
- * Read an environment variable.
- *
- * Trims beginning and trailing whitespace.
- *
- * Will return undefined if the environment variable doesn't exist or cannot be accessed.
- */
-export const readEnv = (env) => {
-    if (typeof globalThis.process !== 'undefined') {
-        return globalThis.process.env?.[env]?.trim() ?? undefined;
-    }
-    if (typeof globalThis.Deno !== 'undefined') {
-        return globalThis.Deno.env?.get?.(env)?.trim();
-    }
-    return undefined;
-};
-//# sourceMappingURL=env.mjs.map