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/mcpb/dist/shared/log.js

@@ -1,29 +0,0 @@
-export function getLogger({ silent = false } = {}) {
-    return {
-        log: (...args) => {
-            if (!silent) {
-                console.log(...args);
-            }
-        },
-        error: (...args) => {
-            if (!silent) {
-                console.error(...args);
-            }
-        },
-        warn: (...args) => {
-            if (!silent) {
-                console.warn(...args);
-            }
-        },
-        info: (...args) => {
-            if (!silent) {
-                console.info(...args);
-            }
-        },
-        debug: (...args) => {
-            if (!silent) {
-                console.debug(...args);
-            }
-        },
-    };
-}