fix: output TypeDoc to tmp/docs/ by default

Running `pnpm run docs` without arguments previously overwrote the
`docs/` directory, which contains project documentation like
`migration.md`. Now it outputs to `tmp/docs/` by default, making it safe
to run manually.

The `generate-gh-pages.sh` script passes `--out` explicitly, so
CI/deployment workflows are unaffected.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: jonathanhefner

.gitignore

@@ -1,3 +1,6 @@
+# Temporary files
+tmp/
+
 # Logs
 logs
 *.log

typedoc.config.mjs

@@ -21,6 +21,7 @@ console.log(
     publicPackages.map(p => p.manifest.name)
 );
 
+/** @type {Partial<import("typedoc").TypeDocOptions>} */
 export default {
     name: 'MCP TypeScript SDK',
     entryPointStrategy: 'packages',
@@ -35,5 +36,6 @@ export default {
     },
     headings: {
         readme: false
-    }
+    },
+    out: 'tmp/docs/',
 };