feat: universal LLM gateway with embedded multilingual admin console

- OpenAI-compatible gateway with intelligent routing via cortiq-router (allaigate)
- Embedded build-free admin SPA at /admin: 7 languages (en/ru/de/fr/es/zh/tr),
  light/dark themes, hot config reload (no restart)
- Admin API, per-request statistics + Prometheus /metrics, secret store, playground
- English documentation (primary) with Russian translations (*.ru.md)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -0,0 +1,35 @@
+# Changelog
+
+All notable changes to this project are documented here.
+The format is based on [Keep a Changelog](https://keepachangelog.com/).
+
+## [Unreleased]
+
+### Added
+- **Embedded admin web console** at `/admin` — a build-free single-page app compiled
+  into the binary via `rust-embed`. Manage models, routing, protocols, virtual keys
+  and secrets from the browser; changes are hot-reloaded (no restart).
+- **Multilingual UI** in 7 languages (en, ru, de, fr, es, zh, tr) with browser
+  auto-detection, plus light/dark themes.
+- **Admin API** under `/admin/api/*` (Bearer admin token): config, models (CRUD +
+  probe), routing, protocols, settings, keys, secrets, stats, requests, and a
+  playground `test` endpoint.
+- **Hot config reload** — config-derived state lives behind `arc-swap`; writes
+  validate → atomically rewrite the TOML → swap, with no restart.
+- **Request statistics** — in-memory aggregates, per-minute time buckets, and a ring
+  buffer of recent requests, appended to a JSONL file and replayed on startup.
+- **Prometheus `GET /metrics`** endpoint.
+- **Secret store** (`config/secrets.toml`, mode `0600`) — provider keys can be set
+  from the UI without writing them into `gateway.toml`; values are never returned by
+  the API.
+- English documentation as the primary language, with Russian translations
+  (`README.ru.md`, `docs/*.ru.md`).
+
+### Changed
+- The Anthropic provider now returns a clear error instead of panicking when called
+  (the adapter is still planned for v0.2).
+
+## [0.0.1]
+- Initial skeleton: OpenAI Chat Completions inbound adapter, OpenAI-compatible
+  outbound provider, routing table with fallback and graceful degradation, and
+  cost/token accounting.