T-Junction Phase 2 mit 3D Brep Union + Material-Prio-Carve

Asymmetric L-merge fuer Schichtdurchdringung:
- Backbone (= hoechste Material-Prio in beiden Waenden) bildet T-form
- Non-backbone Layer werden gecarved mit backbone-Column + through-Bands
  hoeherer Prio
- ext=0 fuer T-Stem-Axis (= column endet am snap, kein "drueber")
- 3D Brep Union via Brep.CreateBooleanUnion mit cross-junction safety
  (= aktueller through-Brep statt von Meta neu zu bauen)
- Cleanup: MergeCoplanarFaces

Plus:
- Innenwand Beton 20cm Style (Putz + Beton + Putz, ref-mid)
- curve_vertex_dots.py: gruene Vertex-Punkte fuer Polylinen/Curves
- Cluster-Volume Select Handler: Shift-Modifier fuer Multi-Select
- startup.py: Top-View maximieren on Doc-Open

Known limitation: Putz-Schicht kann in bestimmten Konfigurationen visuell
suedlich des Daemm-Band-Top weiter sichtbar sein (= edge case fuer
asymmetric layers). Naechster Schritt: manuelle 2D-Polygon-Konstruktion
statt 3D Boolean.

rhino/startup.py

@@ -151,6 +151,45 @@ def _assign_default_display_modes(doc):
     print("[STARTUP] view-modes: {} Viewport(s) gesetzt".format(n_set))
 
 
+_DOC_FLAG_VIEW_MAXIMIZED = "dossier_top_view_maximized"
+
+
+def _maximize_top_view(doc):
+    """Maximiert den Top-Viewport (= einzige aktive View statt 4-Viewport-
+    Default). Persistiert Flag in doc.Strings → laeuft nur EINMAL pro Doc.
+    User-Overrides (manuelles Wechseln zu 4-View etc) bleiben erhalten."""
+    if doc is None: return
+    try:
+        if doc.Strings.GetValue(_DOC_FLAG_VIEW_MAXIMIZED) == "1":
+            return   # schon initialisiert
+    except Exception: pass
+    try:
+        top_view = None
+        for view in doc.Views:
+            try:
+                vp = view.ActiveViewport
+                if vp is None: continue
+                if vp.Name == "Top":
+                    top_view = view
+                    break
+            except Exception: pass
+        if top_view is None:
+            print("[STARTUP] view-max: kein Top-Viewport gefunden")
+            return
+        try:
+            top_view.Maximized = True
+            doc.Views.ActiveView = top_view
+            doc.Views.Redraw()
+            print("[STARTUP] view-max: Top-Viewport maximiert")
+        except Exception as ex:
+            print("[STARTUP] view-max set:", ex); return
+        try:
+            doc.Strings.SetString(_DOC_FLAG_VIEW_MAXIMIZED, "1")
+        except Exception: pass
+    except Exception as ex:
+        print("[STARTUP] view-max:", ex)
+
+
 _DOC_FLAG_UNIT_CHECKED = "dossier_unit_checked"
 
 
@@ -227,6 +266,7 @@ def _on_doc_opened(sender, e):
         import panel_base
         panel_base.migrate_to_dossier(doc)
         _assign_default_display_modes(doc)
+        _maximize_top_view(doc)
         _check_doc_unit(doc)
     except Exception as ex:
         print("[STARTUP] _on_doc_opened:", ex)
@@ -301,6 +341,11 @@ def _load_all(sender, e):
         _pb._t_mark("post_init", "view_modes", _t_vm)
     except Exception as ex:
         print("[STARTUP] view-modes assign:", ex)
+    # Top-View maximieren (= einzige aktive View statt 4-View Default)
+    try:
+        _maximize_top_view(Rhino.RhinoDoc.ActiveDoc)
+    except Exception as ex:
+        print("[STARTUP] view-max:", ex)
     # Unit-Check fuer das beim Start aktive Doc — fragt einmal pro Doc
     # wenn doc.ModelUnitSystem != Project-Setting
     _t_uc = _t.time()