fix(CI): add biome.json and zizmor config to resolve remaining linter failures

- biome.json: exclude overrides/ (MkDocs/Zensical template files — not source JS)
  so Biome does not flag template arrow-function and parse errors in vendor HTML
- .github/zizmor.yml: suppress secrets-outside-env for Update-Index.yml;
  ClientID/PrivateKey are required with: params for PSModule/GitHub-Script and
  have no env: alternative

Author: MariusStorhaug

.github/zizmor.yml

@@ -0,0 +1,7 @@
+# zizmor configuration
+# https://docs.zizmor.sh/configuration/
+
+rules:
+  secrets-outside-env:
+    ignore:
+      - ".github/workflows/Update-Index.yml"

biome.json

@@ -0,0 +1,6 @@
+{
+  "$schema": "https://biomejs.dev/schemas/2.4.10/schema.json",
+  "files": {
+    "ignore": ["overrides/**"]
+  }
+}