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/node.rs

@@ -0,0 +1,74 @@
+use chrono::{DateTime, Utc};
+use serde::{Deserialize, Serialize};
+use std::collections::HashMap;
+
+/// Runtime state of a single node in the fleet.
+#[derive(Debug, Clone)]
+pub struct NodeState {
+    pub name: String,
+    pub endpoint: String,
+    pub vram_mb: u64,
+    pub pinned: Vec<String>,
+    pub healthy: bool,
+    pub models: HashMap<String, ModelEntry>,
+    /// Number of load/unload cycles since last process restart.
+    pub lifecycle_cycles: u32,
+    pub last_poll: Option<DateTime<Utc>>,
+}
+
+/// A model registered on a node, with its runtime status.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ModelEntry {
+    pub id: String,
+    pub status: ModelStatus,
+    /// When this model was last used (for LRU eviction).
+    pub last_accessed: Option<DateTime<Utc>>,
+    /// Estimated VRAM usage in MB when loaded.
+    pub vram_estimate_mb: Option<u64>,
+}
+
+/// Model lifecycle status, matching the mistral.rs API.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "lowercase")]
+pub enum ModelStatus {
+    Loaded,
+    Unloaded,
+    Reloading,
+}
+
+/// Unified model entry as exposed by the gateway's `/v1/models` endpoint.
+/// Includes which node(s) host this model and their status.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct CortexModelEntry {
+    pub id: String,
+    pub object: String,
+    /// Which nodes have this model (and their status).
+    pub locations: Vec<ModelLocation>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ModelLocation {
+    pub node: String,
+    pub status: ModelStatus,
+    pub vram_estimate_mb: Option<u64>,
+}
+
+/// Response from mistral.rs `GET /v1/models`.
+/// This is the upstream format we parse when polling nodes.
+#[derive(Debug, Clone, Deserialize)]
+pub struct MistralModelsResponse {
+    pub data: Vec<MistralModelEntry>,
+}
+
+#[derive(Debug, Clone, Deserialize)]
+pub struct MistralModelEntry {
+    pub id: String,
+    #[serde(default)]
+    pub status: Option<String>,
+}
+
+/// Request body for mistral.rs model lifecycle endpoints.
+#[derive(Debug, Clone, Serialize)]
+pub struct ModelLifecycleRequest {
+    pub model_id: String,
+}