feat: scaffold cortex workspace

Rust reverse-proxy for multi-node mistral.rs inference clusters.
Includes crate structure (cortex-core, cortex-gateway, cortex-agent,
cortex-cli), config loading, OpenAI/Anthropic translation stubs,
model routing, eviction, polling, and streaming proxy scaffolding.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/cortex-core/src/lib.rs

@@ -0,0 +1,6 @@
+pub mod anthropic;
+pub mod config;
+pub mod metrics;
+pub mod node;
+pub mod openai;
+pub mod translate;