feat(auth): add HTTP Digest authentication plugin (#628)

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

plugins/auth-digest/package.json

@@ -0,0 +1,17 @@
+{
+  "name": "@yaak/auth-digest",
+  "displayName": "Digest Authentication",
+  "version": "0.1.0",
+  "private": true,
+  "description": "Authenticate requests using HTTP Digest authentication",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/mountain-loop/yaak.git",
+    "directory": "plugins/auth-digest"
+  },
+  "scripts": {
+    "build": "yaakcli build",
+    "dev": "yaakcli dev",
+    "test": "vp test --run tests"
+  }
+}