Sprint 35 — 뷰어 IFC 익스포트 연결 + Pset_BeamCommon

## 뷰어 통합
- `cimery-viewer` → `cimery-ifc` 의존성 추가.
- `project_file::scene_params_to_ifc()` 변환 함수:
  SceneParams 의 모든 파라미터(경간 수·교각 형식·skew·헌치·단면 종류·신축이음)
  를 BridgeExportParams 로 전부 매핑.
- egui 프로젝트 섹션에 "📤 IFC4X3 익스포트" 버튼.
  현재 파라미터 상태로 즉시 `projects/bridge.ifc` 생성.
- `project_file::default_ifc_path()` 헬퍼.

## Pset_BeamCommon (IFC Phase 3a)
- `write_pset_beam_common()`: 4개 속성
  · Reference (IFCIDENTIFIER) — 거더 라벨
  · Span (IFCLENGTHMEASURE) — mm
  · LoadBearing (IFCBOOLEAN) — .T.
  · IsExternal (IFCBOOLEAN) — .F.
- IFCRELDEFINESBYPROPERTIES 로 각 IFCBEAM 에 연결.
- `IfcSectionKind` public re-export (viewer 에서 직접 참조).

## 테스트
- pset_beam_common_attached_to_girders 추가. 17개 전체 통과.
- cargo check --workspace --features occt: 0 errors.

Phase 3 남은 로드맵:
- IfcAlignment + IfcLinearPlacement
- Camber 반영 (현재 직선 girder 만)
- Pset_BearingCommon, Pset_SlabCommon
- IfcElementAssembly 로 Pier(column+capbeam) 그룹화

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cimery/crates/ifc/src/bridge_export.rs

@@ -154,16 +154,19 @@ pub fn export_bridge(p: &BridgeExportParams) -> String {
             let profile = write_girder_profile(&mut w, p.section_kind, p.girder_height);
             let shape = write_extrude_shape(&mut w, geom_ctx, profile, span_mm);
             let beam = w.alloc();
+            let girder_label = format!("Girder S{}-G{}", s + 1, i + 1);
             w.emit(
                 beam,
                 &format!(
                     "IFCBEAM({},$,{},$,$,{},{},$,.BEAM.)",
                     lit(&new_ifc_guid()),
-                    lit(&format!("Girder S{}-G{}", s + 1, i + 1)),
+                    lit(&girder_label),
                     placement,
                     shape,
                 ),
             );
+            // Pset_BeamCommon (Sprint 35).
+            write_pset_beam_common(&mut w, beam, &girder_label, span_mm);
             elements.push(beam);
         }
     }
@@ -438,6 +441,46 @@ fn write_girder_profile(
     }
 }
 
+/// Pset_BeamCommon 생성 + `IfcRelDefinesByProperties` 로 beam 에 연결 (Sprint 35 Phase 3a).
+///
+/// # 속성
+/// - `Reference`: 거더 식별자 (프로젝트별 시퀀스)
+/// - `Span`: 경간 길이 [mm] — IfcLengthMeasure
+/// - `LoadBearing`: `.T.` (true)
+/// - `IsExternal`: `.F.`
+fn write_pset_beam_common(
+    w: &mut IfcWriter,
+    beam: Ref,
+    reference: &str,
+    span_mm: f64,
+) {
+    let p_ref = w.write(&format!(
+        "IFCPROPERTYSINGLEVALUE('Reference',$,IFCIDENTIFIER({}),$)",
+        lit(reference),
+    ));
+    let p_span = w.write(&format!(
+        "IFCPROPERTYSINGLEVALUE('Span',$,IFCLENGTHMEASURE({}),$)",
+        real(span_mm),
+    ));
+    let p_lb = w.write(
+        "IFCPROPERTYSINGLEVALUE('LoadBearing',$,IFCBOOLEAN(.T.),$)",
+    );
+    let p_ext = w.write(
+        "IFCPROPERTYSINGLEVALUE('IsExternal',$,IFCBOOLEAN(.F.),$)",
+    );
+    let pset = w.write(&format!(
+        "IFCPROPERTYSET({},$,'Pset_BeamCommon',$,{})",
+        lit(&new_ifc_guid()),
+        ref_list(&[p_ref, p_span, p_lb, p_ext]),
+    ));
+    w.write(&format!(
+        "IFCRELDEFINESBYPROPERTIES({},$,$,$,({}),{})",
+        lit(&new_ifc_guid()),
+        beam,
+        pset,
+    ));
+}
+
 /// Skew 회전 + 평행이동 LocalPlacement — 지점부 요소(교대·피어·받침·joint)에 적용.
 /// skew_rad 는 Y축 중심 회전, pivot_z 기준 반지름 오프셋은 placement origin 에 반영.
 fn write_local_placement_skewed(
@@ -568,6 +611,16 @@ mod tests {
         assert_ne!(zero, skewed);
     }
 
+    #[test]
+    fn pset_beam_common_attached_to_girders() {
+        let ifc = export_bridge(&BridgeExportParams::default());
+        assert!(ifc.contains("IFCPROPERTYSET"), "no Pset emitted");
+        assert!(ifc.contains("'Pset_BeamCommon'"), "Pset name missing");
+        assert!(ifc.contains("IFCRELDEFINESBYPROPERTIES"), "Pset not attached");
+        assert!(ifc.contains("LoadBearing"));
+        assert!(ifc.contains("Span"));
+    }
+
     #[test]
     fn haunch_moves_deck_up() {
         // haunch 0 vs 200 → deck slab 중심 Y 위치가 다름. ifc text diff 로 확인.

cimery/crates/ifc/src/lib.rs

@@ -27,5 +27,5 @@ pub mod writer;
 pub mod guid;
 pub mod bridge_export;
 
-pub use bridge_export::{BridgeExportParams, export_bridge};
+pub use bridge_export::{BridgeExportParams, IfcSectionKind, export_bridge};
 pub use writer::IfcWriter;