fix(rest+llm): /api/v1/consult e2e wiring — env-var port + cartridge name

Closes the deferred /api/v1/consult e2e exercise from 2026-04-25 evening.

Two changes:

1. src/rust/llm.rs — `echidna-llm` → `echidna-llm-mcp` (cartridge name)

   LlmAdvisor was POSTing to `/cartridge/echidna-llm/invoke` but the
   actual BoJ cartridge name is `echidna-llm-mcp` (verified against
   the live BoJ instance at localhost:7700 — `GET /cartridges`
   returns the registered name).  Pre-fix the consult call returned
   404 unknown-cartridge from BoJ; post-fix it reaches the cartridge
   and returns whatever the cartridge handler decides (currently 500
   because BoJ is in skeleton mode — not echidna's responsibility).

2. src/interfaces/rest/main.rs — `ECHIDNA_REST_ADDR` env-var override

   The hardcoded `127.0.0.1:8000` collides with other workspace
   processes (Python SimpleHTTPServer was on 8000 during testing).
   Reading `ECHIDNA_REST_ADDR` lets the server bind a free port for
   ad-hoc e2e exercises without touching the default.

E2E verified path:
  curl POST /api/v1/consult on 127.0.0.1:8765
  → handler validates non-empty question (400 on empty)
  → LlmAdvisor.check_health() succeeds against live BoJ
  → LlmAdvisor.consult() POSTs to BoJ /cartridge/echidna-llm-mcp/invoke
  → BoJ skeleton-mode invoke returns 500
  → handler maps to 502 Bad Gateway with passthrough error message

Echidna side fully wired.  BoJ-side cartridge is a placeholder by
its own self-declared status (`/health` reports `mode: skeleton,
note: invocation is a placeholder`); making BoJ return real LLM
responses is a separate task tracked in boj-server.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: hyperpolymath

src/interfaces/rest/main.rs

@@ -125,11 +125,11 @@ async fn main() {
         .layer(CorsLayer::permissive())
         .with_state(state);
 
-    let addr = "127.0.0.1:8000";
+    let addr = std::env::var("ECHIDNA_REST_ADDR").unwrap_or_else(|_| "127.0.0.1:8000".to_string());
     tracing::info!("REST API listening on http://{}", addr);
     tracing::info!("Swagger UI available at http://{}/swagger-ui", addr);
 
-    let listener = tokio::net::TcpListener::bind(addr).await.unwrap();
+    let listener = tokio::net::TcpListener::bind(&addr).await.unwrap();
     axum::serve(listener, app).await.unwrap();
 }
 

src/rust/llm.rs

@@ -442,7 +442,7 @@ impl LlmAdvisor {
             build_user_prompt(&goal_str, &hypotheses, &self.history, self.config.top_k);
 
         // Call BoJ cartridge invoke endpoint
-        let url = format!("{}/cartridge/echidna-llm/invoke", self.config.boj_url);
+        let url = format!("{}/cartridge/echidna-llm-mcp/invoke", self.config.boj_url);
 
         let request_body = serde_json::json!({
             "operation": "suggest_tactics",
@@ -538,7 +538,7 @@ impl LlmAdvisor {
             bail!("LLM advisor not available — call check_health() first");
         }
 
-        let url = format!("{}/cartridge/echidna-llm/invoke", self.config.boj_url);
+        let url = format!("{}/cartridge/echidna-llm-mcp/invoke", self.config.boj_url);
 
         let request_body = serde_json::json!({
             "operation": "consult",