feat: Add E11 Part Mass extractor, document pyNastran mass accuracy issue

New E11 Part Mass Extractor:
- Add nx_journals/extract_part_mass_material.py - NX journal using
  NXOpen.MeasureManager.NewMassProperties() for accurate geometry-based mass
- Add optimization_engine/extractors/extract_part_mass_material.py - Python
  wrapper that reads JSON output from journal
- Add E11 entry to extractors/catalog.json

Documentation Updates:
- SYS_12_EXTRACTOR_LIBRARY.md: Add mass accuracy warning noting pyNastran
  get_mass_breakdown() under-reports ~7% on hex-dominant meshes with
  tet/pyramid fill elements. E11 (geometry .prt) should be preferred over
  E4 (BDF) unless material is overridden at FEM level.
- 01_CHEATSHEET.md: Add mass extraction tip

V14 Config:
- Expand design variable bounds (blank_backface_angle max 4.5°,
  whiffle_triangle_closeness max 80mm, whiffle_min max 60mm)

Testing showed:
- E11 from .prt: 97.66 kg (accurate - matches NX GUI)
- E4 pyNastran get_mass_breakdown(): 90.73 kg (~7% under-reported)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

studies/m1_mirror_adaptive_V14/1_setup/optimization_config.json

@@ -77,7 +77,7 @@
       "name": "whiffle_min",
       "expression_name": "whiffle_min",
       "min": 30.0,
-      "max": 55.0,
+      "max": 60.0,
       "baseline": 40.55,
       "units": "mm",
       "enabled": true
@@ -95,7 +95,7 @@
       "name": "whiffle_triangle_closeness",
       "expression_name": "whiffle_triangle_closeness",
       "min": 50.0,
-      "max": 65.0,
+      "max": 80.0,
       "baseline": 60.00,
       "units": "mm",
       "enabled": true
@@ -104,7 +104,7 @@
       "name": "blank_backface_angle",
       "expression_name": "blank_backface_angle",
       "min": 4.1,
-      "max": 4.2,
+      "max": 4.5,
       "baseline": 4.15,
       "units": "degrees",
       "enabled": true