rename gateway-* → system-model-* + gateway-messaging, de-ollama, add system-model-explorer

- Rename gateway-provider → system-model-provider (generic :local provider, no hardcoded ollama)
- Rename gateway-llm → system-model (model-request dispatcher)
- Rename system-embedding-gateway → system-model-embedding
- Rename gateway-manager → gateway-messaging (public api renamed to messaging-*)
- Add system-model-explorer (model discovery via OpenRouter API, cached, per-slot recommendations)
- Fix skill loader export: replace prefix-matching with fbound/boundp-based export (20 skills now export)
- Add model-router to skill-loader exclusion list (loaded via CLI)
- De-ollama: remove hardcoded assumed-available patterns from provider pipeline
- Default cascade: cloud-only (openrouter, openai, groq, gemini, deepseek, nvidia, anthropic)
- Env example: add LOCAL_BASE_URL, fix cascade order
- All org files updated with architectural prose (literate programming)

org/system-archivist.org

@@ -290,10 +290,10 @@ Triggered by heartbeat events, runs Scribe and Gardener on alternating schedules
 
 ;; REPL-VERIFIED: 2026-05-03T13:00:00
 #+begin_src lisp
-(defun archivist-run (context)
+(defun archivist-run (action context)
   "Runs the archivist maintenance cycle. Checks Scribe and Gardener schedules
 and dispatches as needed. Called by the deterministic gate."
-  (declare (ignore context))
+  (declare (ignore action context))
   (let ((now (get-universal-time)))
     ;; Scribe runs every 6 hours (21600 seconds)
     (when (>= (- now *archivist-last-scribe*) 21600)