feat(understand): drawing_topology_check and the three topo_* critique focuses

engineering/understand/topology.py reads a line network (LINE, polylines
with true bulge arcs, ARC) on the chosen layers and reports dangling
ends, near misses (end-end and end-segment within gap, one row per pair)
and interior crossings of two straight segments of one layer. An end on
another network line is joined; an end on any curve of another layer or
inside a block reference's box is attached; a line drawn twice is not a
join, so a doubled pipe still dangles. gap defaults to 0.2 % of the
network diagonal, never under ten tol.

drawing_topology_check joins drawing_diff in SECTION 26: default layers
are those classify_layer calls piping or electrical at >= 0.9, reported
with their classification; no such layer is a refusal, not a pass.

topo_dangling_endpoint (warning), topo_near_miss (error) and
topo_interior_crossing (info) join the closed enum and run under
focus=None, excluding the P&ID and architectural layer sets, so a
pid_from_spec sheet and an arch_plan_from_spec plan get none of them;
a drawing with no candidate layer is never snapshotted.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FKFStjEFzpGyLq5bMpWxTd

docs/tool-inventory.json

@@ -3,13 +3,13 @@
   "schema_version": 1,
   "package_version": "1.5.1",
   "totals": {
-    "tools": 242,
+    "tools": 243,
     "resources": 8,
     "prompts": 5,
     "groups": 26
   },
   "groups": {
-    "analysis": 13,
+    "analysis": 14,
     "architecture": 12,
     "batch": 3,
     "blocks": 9,
@@ -1175,6 +1175,20 @@
         "destructiveHint": false
       }
     },
+    {
+      "name": "drawing_topology_check",
+      "group": "analysis",
+      "cost": "read",
+      "summary": "Find dangling ends, near misses and unjoined crossings in a pipe or cable network.",
+      "tags": [
+        "analysis",
+        "query"
+      ],
+      "annotations": {
+        "title": "Drawing: Topology Check",
+        "readOnlyHint": true
+      }
+    },
     {
       "name": "drawing_undo",
       "group": "drawing",