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

.gitleaks.toml

@@ -0,0 +1,14 @@
+# Gitleaks configuration for this monorepo.
+# Docs: https://github.com/gitleaks/gitleaks#configuration
+
+title = "gitleaks config"
+
+[extend]
+# Use the upstream default ruleset as the base.
+useDefault = true
+
+[allowlist]
+description = "Test fixtures in __seeds__ directories use token-shaped dummy strings that are not real credentials."
+paths = [
+  '''__seeds__/''',
+]