Author runnable skill bodies via OpenAI-compatible codegen model

create_skill now writes a real predict/act body: the small decision model
still authors title + description (engine.generate), then a larger
OpenAI-compatible model (default qwen38-iq3s) writes the runnable code
against the SKILL.md contract. Bodies persist to data/skills/<cat>/<name>.py,
are hot-loaded via importlib, merged into the running tree, and the request
re-dispatches to the new leaf. The dashboard decision-flow view shows the
title/description with a writing badge while the body is being written.
Codegen failure degrades to a navigable stub.

config.example.json

@@ -12,6 +12,13 @@
     "threads": 8
   },
   "llm": {"base_url": "http://localhost:11434/v1", "model": "qwen3.5:4b"},
+  "codegen": {
+    "_comment": "OpenAI-compatible model that writes runnable skill bodies. Larger/slower than the decision or self-assessment model.",
+    "base_url": "http://localhost:11434/v1",
+    "model": "qwen38-iq3s",
+    "timeout": 600
+  },
+  "skill_bodies": "data/skills",
   "skills": {
     "email": {"cost_budget": 1.0},
     "contacts": "data/contacts.json",