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>

src/protocols/mod.rs

@@ -0,0 +1,17 @@
+//! Incoming protocol adapters. Each one builds its own axum routes and translates
+//! its protocol to/from the canonical model. Enabled via flags in `[protocols]`.
+
+pub mod openai_chat;
+
+use crate::state::SharedState;
+use axum::Router;
+
+/// Build the protocols router. Implemented adapters are **always** mounted;
+/// each handler checks the live `protocols.*` flag from config itself, so
+/// toggles in the admin panel take effect without a restart (hot switching).
+pub fn build_router() -> Router<SharedState> {
+    Router::new().merge(openai_chat::routes())
+    // TODO: openai_completions, openai_embeddings, openai_models,
+    //       anthropic_messages, mcp, native_passthrough — add here as well,
+    //       with a check of the corresponding flag inside the handler.
+}