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

tests/test_tool_registry.py

@@ -495,7 +495,7 @@ async def test_tool_groups_is_byte_identical_to_the_source_declared_grouping():
 
 
 async def test_tool_group_sizes_are_unchanged():
-    """Frozen snapshot of the surface (242 tools, 26 groups).
+    """Frozen snapshot of the surface (243 tools, 26 groups).
 
     Taken before @cad_tool landed at 131 tools; `batch` moved 2 -> 3 when
     v1.5.0's `cad_batch` joined `entity_batch_create`/`entity_batch_modify`, and
@@ -595,13 +595,14 @@ async def test_tool_group_sizes_are_unchanged():
     Track H group U opened SECTION 26 (Understanding & QA) with
     `drawing_understand`, tagged `analysis` and `query`: `analysis` outranks
     `query` in `_GROUP_TAG_PRIORITY`, so the reader files under `analysis`
-    (12 -> 13) beside the other whole-drawing queries. This snapshot is
-    branch-local: the track H merge task recomputes it once the understand,
-    network and diff branches have landed.
+    (12 -> 13) beside the other whole-drawing queries, and
+    `drawing_scale_check`, tagged the same, followed it (13 -> 14). This
+    snapshot is branch-local: the track H merge task recomputes it once the
+    understand, network and diff branches have landed.
     """
     sizes = {label: len(names) for label, names in (await server._tool_groups()).items()}
     assert sizes == {
-        "analysis": 13,
+        "analysis": 14,
         "architecture": 12,
         "batch": 3,
         "blocks": 9,
@@ -628,4 +629,4 @@ async def test_tool_group_sizes_are_unchanged():
         "validation": 1,
         "view": 4,
     }
-    assert sum(sizes.values()) == 242
+    assert sum(sizes.values()) == 243