feat(templates): five bundled templates built by the server's own tools; drawing_new(template=name)

SECTION 19 grows to five tools with drawing_template_list; drawing_new takes a
bundled name (iso_a3_mech, iso_a1_arch, iso_a3_pid, ansi_b_mech, ansi_d_arch)
or a .dwt/.dxf path and reports template: {name|path, path, source}.

scripts/build_templates.py builds templates/*.dxf through EzdxfBackend
(layer set, header DIM variables until group S's styles land, drawing_settings,
sheet tab, ISO 5457 frame on A3, page_setup_apply) and --check pins them
reproducible. One drift the plan's same-process measurement could not see is
fixed at the source rather than masked: ezdxf orders CLASSES by set iteration,
so two processes disagreed on LAYOUT / ACDBPLACEHOLDER; the section is re-keyed
(required list first, then by name) before the save.

The root .gitignore ignores *.dxf as generated output; templates/*.dxf is
un-ignored there, since the bundled set is the one DXF that is committed.

Co-Authored-By: Claude Opus 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 (170 tools, 20 groups).
+    """Frozen snapshot of the surface (171 tools, 20 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
@@ -521,8 +521,10 @@ async def test_tool_group_sizes_are_unchanged():
     `layouts` moved 12 -> 16 when v1.6's SECTION 19 opened with
     `page_setup_list` / `page_setup_apply` / `plot_style_list` / `batch_plot`
     — all tagged `layout`, which `_GROUP_TAG_PRIORITY` ranks above
-    `query`/`export`, so they file with the sheets they set up. Every
-    other number here has been unchanged since the snapshot was taken.
+    `query`/`export`, so they file with the sheets they set up. `templates`
+    moved 2 -> 3 when v1.6's `drawing_template_list` joined SECTION 19
+    (tagged `template`, which ranks above `drawing`). Every other number
+    here has been unchanged since the snapshot was taken.
     """
     sizes = {label: len(names) for label, names in (await server._tool_groups()).items()}
     assert sizes == {
@@ -542,9 +544,9 @@ async def test_tool_group_sizes_are_unchanged():
         "premium": 12,
         "solids": 5,
         "system": 7,
-        "templates": 2,
+        "templates": 3,
         "transactions": 3,
         "validation": 1,
         "view": 4,
     }
-    assert sum(sizes.values()) == 170
+    assert sum(sizes.values()) == 171