fix(deploy): add netlify.toml to use pnpm for docs build

Dashboard cmd still ran "yarn workspace docs build" — broken since
the pnpm migration removed yarn.lock (deploys failing since Apr 3).
Override via netlify.toml: pnpm --filter docs build, Node 22.
Also ignore local .netlify/ state dir created by netlify CLI.

Author: gunnartorfis

.gitignore

@@ -84,3 +84,6 @@ docs/.envrc
 
 # Claude Code
 .claude/
+
+# Local Netlify folder
+.netlify

netlify.toml

@@ -0,0 +1,6 @@
+[build]
+  command = "pnpm --filter docs build"
+  publish = "docs/build"
+
+[build.environment]
+  NODE_VERSION = "22"