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/core-communication.org

@@ -205,6 +205,15 @@ Validates that an incoming message has the minimum required structure: a plist w
     t))
 #+end_src
 
+** Backward-Compatibility Alias
+
+;; REPL-VERIFIED: 2026-05-03T14:00:00
+#+begin_src lisp
+(defun validate-communication-protocol-schema (msg)
+  "Backward-compatibility alias for protocol-schema-validate."
+  (protocol-schema-validate msg))
+#+end_src
+
 ** Protocol Smoke Test (manual for REPL evaluation)
 
 Use this function to manually verify that the daemon is alive and the framing protocol works end-to-end. It connects to a running daemon, reads the HELLO handshake, sends a "hi" message, and reads the response.