The new loop's core: intake, restatement, go-ahead, threads (M2.1, PR B)

nisse_dev.loop runs alongside control.py, chosen with `loop: new`.
Issues assigned to the agent (by an operator, or filed by one) become work
items, each with a Matrix thread. A driver run is one model with tools
until it calls a waiting tool: restate puts rev-N up for a go-ahead, bound
to the revision on screen when the reply arrived; ask_human waits for an
answer; close_item closes the item and its issue. Before the go-ahead the
driver can look but not change or close anything. One item is active at a
time; replies in an item's thread go to it. On boot, an item cut off
mid-run waits on the operator, and waiting points are put up again.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPQ14L3LikyefCMFBqEbKE

nisse-dev.example.yaml

@@ -11,6 +11,7 @@
 state_db: ~/nisse-demo-workspace/state.db
 workspace: /root/work/demo           # the clone, on the build host
 project: demo
+# loop: new          # the new conversational loop (M2.1); default old (control.py)
 
 build_host:                          # L13: every command runs here, over SSH
   address: build-demo.example