Fix zlayout_shared target build configuration

- Remove circular dependency between zlayout and zlayout_shared targets
- Add proper include directories and compiler flags to zlayout_shared
- Update CI workflow to build targets sequentially for better error handling
- Fix 'invalid argument: zlayout_shared' error in CI builds

Author: WenyinWei

.github/workflows/docs.yml

@@ -157,11 +157,27 @@ jobs:
     - name: Build C++ library
       run: |
         Write-Host "Building C++ library..."
-        xmake build zlayout zlayout_shared basic_example
+        # Build core library first
+        xmake build zlayout
         if (-not $?) { 
-          Write-Host "C++ library build failed"
+          Write-Host "Static library build failed"
           exit 1 
         }
+        
+        # Build shared library
+        xmake build zlayout_shared
+        if (-not $?) { 
+          Write-Host "Shared library build failed"
+          exit 1 
+        }
+        
+        # Build examples
+        xmake build basic_example
+        if (-not $?) { 
+          Write-Host "Examples build failed"
+          exit 1 
+        }
+        
         Write-Host "C++ library build completed successfully"
     
     - name: Run C++ tests

xmake.lua

@@ -99,11 +99,28 @@ target("zlayout")
 -- Shared library version
 target("zlayout_shared")
     set_kind("shared")
-    add_deps("zlayout")
     add_files("src/zlayout.cpp")
     add_files("src/geometry/*.cpp")
     add_files("src/spatial/*.cpp")
-    add_defines("ZLAYOUT_SHARED")
+    add_headerfiles("include/zlayout/**.hpp")
+    
+    -- Add include directories
+    add_includedirs("include")
+    add_includedirs("include/zlayout")
+    
+    -- Math optimization (Linux/Unix only)
+    if is_plat("linux", "macosx") then
+        add_links("m")  -- Link math library
+    end
+    
+    -- Optional OpenMP support for parallel processing
+    if has_config("openmp") then
+        add_packages("openmp")
+        add_defines("ZLAYOUT_OPENMP")
+    end
+    
+    -- Export symbols for shared library
+    add_defines("ZLAYOUT_EXPORTS", "ZLAYOUT_SHARED")
 
 -- Visualization library (optional)
 if has_config("with-visualization") then