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/sandbox-runtime/dist/utils/debug.js

@@ -1,25 +0,0 @@
-/**
- * Simple debug logging for standalone sandbox
- */
-export function logForDebugging(message, options) {
-    // Only log if SRT_DEBUG environment variable is set
-    // Using SRT_DEBUG instead of DEBUG to avoid conflicts with other tools
-    // (DEBUG is commonly used by Node.js debug libraries and VS Code)
-    if (!process.env.SRT_DEBUG) {
-        return;
-    }
-    const level = options?.level || 'info';
-    const prefix = '[SandboxDebug]';
-    // Always use stderr to avoid corrupting stdout JSON streams
-    switch (level) {
-        case 'error':
-            console.error(`${prefix} ${message}`);
-            break;
-        case 'warn':
-            console.warn(`${prefix} ${message}`);
-            break;
-        default:
-            console.error(`${prefix} ${message}`);
-    }
-}
-//# sourceMappingURL=debug.js.map