feat(server): tool profiles, paper-space layouts + viewports, ISO 286 fits, opt-in COM 3D solids

- TOOL_PROFILE=lean|core|full applied in the lifespan via server-level enable/disable; system_about reports the active profile; opt-in solid_* tools are hidden while ENABLE_3D=false
- layouts: layout_list/create/set_current + viewport_create (scaled model viewports) on both backends; drawing_export_pdf(layout=...); ezdxf uses TILEMODE + active-layout binding, COM switches ActiveLayout and restores it
- ISO 286: engineering/fits.py authored IT4-11 + fundamental-deviation tables (1-500 mm; shafts d..p/h/js, holes D..H/JS) with clear out-of-scope errors; dimension_linear/radius/diameter gained fit= resolved from the measured nominal
- tolerances: DIMTM now signed in deviation/limit modes so double-positive fits (p6 +0.035/+0.022) render correctly; legacy positive-magnitude contract preserved
- solids: solid_box/cylinder/extrude/revolve/boolean native on COM (AddBox/AddCylinder/AddRegion+AddExtrudedSolid/AddRevolvedSolid/Boolean); ezdxf reports the honest solid_3d capability boundary
- capability maps: paper_space native, new viewport_render feature, ENABLE_3D-gated solid_3d
- 60 new tests (profiles, layouts, viewports, layout PDF, fits, gating); version pins in tests now read version.__version__

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_capabilities.py

@@ -5,6 +5,7 @@ from unittest.mock import patch
 import pytest
 
 from backends.base import CapabilityMap, FeatureCapability
+from version import __version__
 
 
 def test_capability_types_serialize_stably():
@@ -32,7 +33,11 @@ async def test_ezdxf_capabilities_are_machine_readable(backend):
         "reason": None,
     }
     assert caps["features"]["mleader"]["mode"] == "composite"
-    assert caps["features"]["paper_space"]["supported"] is False
+    # v1.4: paper-space layouts/viewports are native on both backends;
+    # projecting model content through viewports stays COM-only, and 3D
+    # ACIS solids remain impossible headlessly.
+    assert caps["features"]["paper_space"]["supported"] is True
+    assert caps["features"]["viewport_render"]["supported"] is False
     assert caps["features"]["solid_3d"]["supported"] is False
 
 
@@ -70,5 +75,5 @@ async def test_system_about_uses_package_version_and_capability_summary(backend)
 
     result = await server.system_about(ctx=Ctx())
 
-    assert result["version"] == "1.3.0"
+    assert result["version"] == __version__
     assert result["capabilities"]["table"]["mode"] == "composite"