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-context.js

@@ -0,0 +1,18 @@
+import { useCaseNameFromFile } from "./_usecase-name.js";
+import { featureRootForFile } from "./_manifest-source.js";
+
+/**
+ * Resolves the rule execution context from an ESLint context object.
+ * Returns null when the file is not a use-case file or not inside a
+ * recognised feature package — callers should return {} immediately.
+ */
+export function resolveRuleContext(context) {
+  const opts = context.options[0] ?? {};
+  const repoRoot = opts.repoRoot ?? context.cwd ?? process.cwd();
+  const filename = context.filename;
+  const useCaseName = useCaseNameFromFile(filename);
+  if (!useCaseName) return null;
+  const featureRoot = featureRootForFile(filename, repoRoot);
+  if (!featureRoot) return null;
+  return { useCaseName, featureRoot, repoRoot };
+}