Fix create_skill wedge: short-circuit single-option navigation, never leave scheduler busy

An empty category produced a one-option SemIf leaf decision; the backend rejects
<2 options, the ValueError unwound past the current-process reset, and every
later request queued forever behind a phantom current. Navigation now
short-circuits empty trees/categories straight to the create branch (no SemIf
decision when there's nothing to choose), and the scheduler clears its current
process even when dispatch raises. Authoring generation is capped at 128 tokens.

semif_agent/scheduler.py

@@ -152,8 +152,10 @@ class Scheduler:
         if self.current is None:
             weight, label = self._score(request)
             self.current = Process(request=request, skill="(scheduling)", weight=weight)
-            outcome = self._dispatch(request)
-            self.current = None
+            try:
+                outcome = self._dispatch(request)
+            finally:
+                self.current = None
             self.trace.append("ran", request.id, skill=outcome.skill, summary=outcome.summary)
             return "running", f"[{label}] {outcome.summary}"
 
@@ -197,7 +199,11 @@ class Scheduler:
                 outcome = self._dispatch(request)
             except EngineUnavailable as exc:
                 outcome = DispatchResult(kind="error", summary=f"engine unavailable: {exc}")
-            self.current = None
+            except Exception as exc:
+                self.trace.append("error", request.id, phase="dispatch", message=str(exc))
+                outcome = DispatchResult(kind="error", summary=f"dispatch failed: {exc}")
+            finally:
+                self.current = None
             self.trace.append("ran", request.id, skill=outcome.skill, summary=outcome.summary)
             results.append(("ran", f"[{request.id}] {outcome.summary}"))
         return results