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/@azure/msal-node/dist/retry/LinearRetryStrategy.mjs

@@ -1,36 +0,0 @@
-/*! @azure/msal-node v3.8.1 2025-10-29 */
-'use strict';
-/*
- * Copyright (c) Microsoft Corporation. All rights reserved.
- * Licensed under the MIT License.
- */
-class LinearRetryStrategy {
-    /**
-     * Calculates the number of milliseconds to sleep based on the `retry-after` HTTP header.
-     *
-     * @param retryHeader - The value of the `retry-after` HTTP header. This can be either a number of seconds
-     *                      or an HTTP date string.
-     * @returns The number of milliseconds to sleep before retrying the request. If the `retry-after` header is not
-     *          present or cannot be parsed, returns 0.
-     */
-    calculateDelay(retryHeader, minimumDelay) {
-        if (!retryHeader) {
-            return minimumDelay;
-        }
-        // retry-after header is in seconds
-        let millisToSleep = Math.round(parseFloat(retryHeader) * 1000);
-        /*
-         * retry-after header is in HTTP Date format
-         * <day-name>, <day> <month> <year> <hour>:<minute>:<second> GMT
-         */
-        if (isNaN(millisToSleep)) {
-            // .valueOf() is needed to subtract dates in TypeScript
-            millisToSleep =
-                new Date(retryHeader).valueOf() - new Date().valueOf();
-        }
-        return Math.max(minimumDelay, millisToSleep);
-    }
-}
-
-export { LinearRetryStrategy };
-//# sourceMappingURL=LinearRetryStrategy.mjs.map