chore(template): clean-slate template snapshot from bb4a0c7

Curated, product-agnostic snapshot of the post-story-04 tree: demo
content deleted, auth-only reference feature, web-next shell, all gates
green. Product-specific docs, ADRs 027-029, PRDs/epics/archive, editor
library traces, and product naming are curated out; generic template
repairs (coverage provider devDeps, root test:coverage script, live
lint fixes, root-only release-please) are kept. See TEMPLATE.md for
provenance, curation list, and usage.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016j8z4VHjedXDTjEDNg7qHK

packages/core-eslint/rules/_rule-schema.js

@@ -0,0 +1,8 @@
+/** Shared repoRoot option schema used by conformance rules that need to locate feature roots. */
+export const repoRootSchema = [
+  {
+    type: "object",
+    properties: { repoRoot: { type: "string" } },
+    additionalProperties: false,
+  },
+];