feat(automation): query op — list entities with detail and filters

Add a query op to the headless server: list entities with handle, type,
layer and basic geometry (Line start/end, Circle/Arc centre+radius, Point
location), filtered by type and/or layer and capped by limit. Closes the
observe half of an agent's act/observe loop. ocs.py gains ocs.query().

Co-Authored-By: Claude Opus 4.8 <[email protected]>

docs/automation/README.md

@@ -19,6 +19,7 @@ can act → observe → act.
 | `{"op":"open","path":"plan.dwg"}` | entity summary |
 | `{"op":"run","cmd":"LAYER Walls"}` | `{"ok":true,"cmd":...,"entities":N,"added":D}` |
 | `{"op":"entities"}` | `{"ok":true,"total":N,"by_type":{"Line":42,...}}` |
+| `{"op":"query","type":"Line","layer":"Walls"}` | per-entity `{handle,type,layer,…geometry}` (filters + `limit` optional) |
 | `{"op":"save","path":"out.dwg"}` | `{"ok":true,"saved":"out.dwg"}` (path optional once opened/saved) |
 
 Every response has `"ok"`; failures carry `"error"`. `run` drives Open CAD

docs/automation/ocs.py

@@ -70,6 +70,15 @@ class Ocs:
         """Total entity count and a breakdown by type."""
         return self._send(op="entities")
 
+    def query(
+        self,
+        type: Optional[str] = None,
+        layer: Optional[str] = None,
+        limit: Optional[int] = None,
+    ) -> dict[str, Any]:
+        """List entities (handle, type, layer, geometry), optionally filtered."""
+        return self._send(op="query", type=type, layer=layer, limit=limit)
+
     def save(self, path: Optional[str] = None) -> dict[str, Any]:
         """Write the document (defaults to the opened/last-saved path)."""
         return self._send(op="save", path=path)