chore: adopt engineering standard v1.0.0

Adopt the org engineering standard (its-consulting/standards @ v1.0.0).

Adds baseline governance/CI/policy files rendered from the standard's
templates and pins .standards-version=1.0.0. Vendored OPA/Rego policies
under .standards/policies/ so CI runs the gate locally (no cross-repo dep).
Placeholders ({{ORG}}/{{REPO}}/{{OWNER_HANDLE}}/{{MAINTAINER_EMAIL}}) filled in.
Existing files that differ were left untouched by the adopter.

Automated rollout. Files created: 15.

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,13 @@
+# Issue chooser config — rendered into <repo>/.github/ISSUE_TEMPLATE/ by
+# adopt-standard.sh. Disables blank issues so every report uses a template,
+# and routes security reports away from the public tracker.
+blank_issues_enabled: false
+contact_links:
+  - name: Security vulnerability (private)
+    url: https://github.com/its-consulting/Homeassistant/security/advisories/new
+    about: >-
+      Do NOT open a public issue for a security problem. Report privately per
+      SECURITY.md (no secrets/keys/tokens in the report; rotate first if leaked).
+  - name: Question / discussion
+    url: https://github.com/its-consulting/Homeassistant/discussions
+    about: For usage questions and open-ended discussion, use Discussions.