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_delivery.py

@@ -10,6 +10,7 @@ import pytest
 import server
 from engineering.delivery import compare_drawing_snapshots, deliver_drawing, drawing_snapshot
 from engineering.layers import ensure_engineering_layers, ensure_standard_linetypes
+from version import __version__
 
 
 async def _clean_drawing(backend) -> None:
@@ -42,7 +43,7 @@ async def test_delivery_writes_hashed_manifest_and_reopen_parity(backend, tmp_pa
     assert dxf["status"] == "created"
     assert dxf["sha256"] == hashlib.sha256(artifact_path.read_bytes()).hexdigest()
     assert manifest["parity"]["ok"] is True
-    assert manifest["version"] == "1.3.0"
+    assert manifest["version"] == __version__
     assert manifest["capabilities"]["backend"] == "ezdxf"
 
 
@@ -107,9 +108,7 @@ async def test_snapshot_parity_rejects_incomplete_entity_inventory(backend, monk
     assert source["listed_entity_count"] == 1
     assert source["inventory_complete"] is False
     assert result["ok"] is False
-    assert "source_inventory_complete" in {
-        item["field"] for item in result["differences"]
-    }
+    assert "source_inventory_complete" in {item["field"] for item in result["differences"]}
 
 
 @pytest.mark.asyncio