Initial commit: web-app boilerplate with auth, OIDC/SSO, admin panel, i18n

Rust (cot framework) + PostgreSQL boilerplate providing:

- Session-based auth with Admin/User roles
- OIDC/SSO login with PKCE, group-to-role mapping, auto-provisioning
- Admin panel: user management, settings, debug/config inspector
- 3-tier config system (compiled default → DB → FURU_* env vars)
- i18n (English + Russian) with compile-time translations macro
- JSON API skeleton (GET /api/me)
- DB-backed sessions (survive server restarts)

Co-Authored-By: Claude <noreply@anthropic.com>

templates/admin/index.html

@@ -0,0 +1,8 @@
+{% extends "admin/layout.html" %}
+
+{% block admin_title %}{{ t.nav_dashboard }}{% endblock admin_title %}
+
+{% block content %}
+<h1>{{ t.admin_heading }}</h1>
+<p><a href="/admin/debug">{{ t.admin_debug_link }}</a></p>
+{% endblock content %}