feat: add DeepSeek and NVIDIA NIM providers

- Add deepseek and nvidia entries to gateway-provider config

- Add DEEPSEEK_API_KEY and NVIDIA_API_KEY to .env.example

- Add deepseek and nvidia to doctor's LLM provider check

- Fix remaining harness-log → log-message reference

lisp/system-archivist.lisp

@@ -0,0 +1,10 @@
+(defun archivist-log (signal)
+  "Logs a metabolic signal for later analysis."
+  (let ((type (getf signal :type))
+        (payload (getf signal :payload)))
+    (harness-log "SCRIBE: [~a] ~s" type payload)))
+
+(defskill :passepartout-system-archivist
+  :priority 100
+  :trigger (lambda (ctx) (member (getf ctx :type) '(:LOG :STATUS)))
+  :deterministic (lambda (action ctx) (declare (ignore action)) (archivist-log ctx) nil))