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_fits.py

@@ -0,0 +1,118 @@
+"""ISO 286 fit-table lookups pinned against published table values."""
+
+from __future__ import annotations
+
+import pytest
+from fastmcp.exceptions import ToolError
+
+from engineering.fits import FitDeviation, fit_lookup, parse_fit_code
+from engineering.tolerances import build_dim_override
+from server import _fit_to_tolerances
+
+
+def _um(value_mm: float) -> float:
+    return round(value_mm * 1000.0, 3)
+
+
+# (code, nominal, upper µm, lower µm) — published ISO 286-2 values.
+CANONICAL_FITS = [
+    ("H7", 20.0, 21, 0),
+    ("H7", 40.0, 25, 0),
+    ("H8", 30.0, 33, 0),
+    ("H9", 6.0, 30, 0),
+    ("H7", 200.0, 46, 0),
+    ("g6", 20.0, -7, -20),
+    ("g6", 6.0, -4, -12),
+    ("f7", 40.0, -25, -50),
+    ("e8", 25.0, -40, -73),
+    ("d9", 100.0, -120, -207),
+    ("h6", 30.0, 0, -13),  # 30 mm is inside the >18-30 step (inclusive upper bound)
+    ("h7", 50.0, 0, -25),
+    ("k6", 20.0, 15, 2),
+    ("m6", 25.0, 21, 8),
+    ("n6", 20.0, 28, 15),
+    ("p6", 20.0, 35, 22),
+    ("js9", 25.0, 26, -26),
+    ("G7", 6.0, 16, 4),
+    ("F8", 40.0, 64, 25),
+    ("D10", 30.0, 149, 65),
+]
+
+
+@pytest.mark.parametrize("code,nominal,upper_um,lower_um", CANONICAL_FITS)
+def test_canonical_fit_values(code, nominal, upper_um, lower_um):
+    deviation = fit_lookup(code, nominal)
+    assert isinstance(deviation, FitDeviation)
+    assert _um(deviation.upper_mm) == pytest.approx(upper_um), f"{code}@{nominal} upper"
+    assert _um(deviation.lower_mm) == pytest.approx(lower_um), f"{code}@{nominal} lower"
+
+
+def test_k_outside_it4_to_7_has_zero_lower_deviation():
+    deviation = fit_lookup("k9", 20.0)
+    assert deviation.lower_mm == 0.0
+    assert _um(deviation.upper_mm) == 52  # IT9 @ 18-30
+
+
+def test_parse_fit_code():
+    assert parse_fit_code("H7") == ("H", 7)
+    assert parse_fit_code("js10") == ("js", 10)
+    with pytest.raises(ValueError):
+        parse_fit_code("77")
+    with pytest.raises(ValueError):
+        parse_fit_code("")
+
+
+@pytest.mark.parametrize(
+    "code,nominal",
+    [
+        ("K7", 20.0),  # transition hole letters need the delta-rule — excluded
+        ("P7", 20.0),
+        ("x6", 20.0),  # letter outside the authored subset (regex rejects)
+        ("H3", 20.0),  # grade below authored range
+        ("H12", 20.0),  # grade above authored range
+        ("H7", 0.5),  # below 1 mm
+        ("H7", 600.0),  # above 500 mm
+    ],
+)
+def test_out_of_scope_lookups_raise(code, nominal):
+    with pytest.raises(ValueError):
+        fit_lookup(code, nominal)
+
+
+def test_double_positive_fit_renders_correct_dimvars():
+    """p6-style fits (+upper/+lower) must produce a negative DIMTM so AutoCAD
+    displays the plus lower deviation."""
+    deviation = fit_lookup("p6", 20.0)
+    override, _ = build_dim_override(
+        tol_upper=deviation.upper_mm,
+        tol_lower=-deviation.lower_mm,  # server convention: positive = minus
+        tol_mode="deviation",
+    )
+    assert override["dimtp"] == pytest.approx(0.035)
+    assert override["dimtm"] == pytest.approx(-0.022)  # displayed as +0.022
+
+
+def test_fit_to_tolerances_contract():
+    tol_upper, tol_lower, tol_mode, text = _fit_to_tolerances("H7", 20.0, None, None, "none", None)
+    assert tol_upper == pytest.approx(0.021)
+    assert tol_lower == pytest.approx(0.0)
+    assert tol_mode == "deviation"
+    assert text == "<> H7"
+
+
+def test_fit_to_tolerances_rejects_mixed_usage():
+    with pytest.raises(ToolError):
+        _fit_to_tolerances("H7", 20.0, 0.1, None, "none", None)
+    with pytest.raises(ToolError):
+        _fit_to_tolerances("H7", 20.0, None, None, "symmetric", None)
+    with pytest.raises(ToolError):
+        _fit_to_tolerances("Q9", 20.0, None, None, "none", None)
+
+
+def test_fit_passthrough_without_code():
+    assert _fit_to_tolerances(None, 20.0, 0.1, 0.05, "deviation", "x") == (
+        0.1,
+        0.05,
+        "deviation",
+        "x",
+    )