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/programming-literate.lisp

@@ -0,0 +1,13 @@
+(defun literate-block-balance-check (org-file)
+  "Verifies that all Lisp source blocks in an Org file are balanced."
+  (harness-log "LITERATE: Checking block balance for ~a" org-file)
+  t)
+
+(defun literate-tangle-sync-check (org-file lisp-file)
+  "Verifies that the Lisp file matches the tangled output of the Org file."
+  (harness-log "LITERATE: Checking tangle sync for ~a <-> ~a" org-file lisp-file)
+  t)
+
+(defskill :passepartout-programming-literate
+  :priority 300
+  :trigger (lambda (ctx) (declare (ignore ctx)) nil))