feat(understand): drawing_scale_check - is this drawing to scale against that one

Equipment tags found exactly once in each drawing are matched (a tag
found twice - a plan copy, a legend - is reported ambiguous and takes no
part; two plan copies resolve to the cluster that matches the most
tags). For every pair of matched tags at least min_pair_mm apart on the
reference, the ratio of their distances is taken in millimetres by each
drawing's inferred unit; the median, the quartiles, the share within
+/-10 % of the median, the same per room of the reference, and the
verdict: to_scale (>= 80 %, with its factor), schematic (<= 50 %),
partly, or insufficient under three matched tags.

server.py grows SECTION 26 to two tools with drawing_scale_check (core,
read-only, tagged analysis/query); alias record, inventory, README
release snapshot 243, frozen group sizes (analysis 14).

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,
@@ -1116,6 +1116,20 @@
         "title": "Save As"
       }
     },
+    {
+      "name": "drawing_scale_check",
+      "group": "analysis",
+      "cost": "read",
+      "summary": "Is this drawing to scale against a reference? Tag distances, ratios, a verdict.",
+      "tags": [
+        "analysis",
+        "query"
+      ],
+      "annotations": {
+        "title": "Understand: Scale Check",
+        "readOnlyHint": true
+      }
+    },
     {
       "name": "drawing_settings",
       "group": "system",