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-self-improve-add.lisp

@@ -0,0 +1,18 @@
+(defun self-improve-edit (filepath old-text new-text)
+  "Applies a transformation to a source file."
+  (declare (ignore old-text new-text))
+  (harness-log "SELF-EDIT: Applying changes to ~a" filepath))
+
+(defskill :passepartout-system-self-improve
+  :priority 100
+  :trigger (lambda (ctx) (declare (ignore ctx)) nil))
+
+(defun self-improve-fix (skill-name error-log)
+  "Attempts to diagnose and repair a broken skill."
+  (declare (ignore error-log))
+  (harness-log "SELF-FIX: Attempting repair of ~a..." skill-name))
+
+(defskill :passepartout-system-self-improve
+  :priority 100
+  :trigger (lambda (ctx) (member (getf ctx :type) '(:LOG :EVENT)))
+  :deterministic (lambda (action ctx) (declare (ignore action ctx)) nil))