fix(core): improve Windows compatibility and fix formatting issues

- remove invalid noexcept in format size estimation
- add cross-platform fallback for Unicode box drawing in print
- replace unsafe getenv usage for Windows compatibility
- fix encoding-related warnings on MSVC

Author: GaspardKirira

include/vix/format/Format.hpp

@@ -280,7 +280,7 @@ namespace vix
      * @return Estimated output size.
      */
     [[nodiscard]] inline std::size_t estimate_output_size(std::string_view fmt,
-                                                          const rendered_arg_list &args) noexcept
+                                                          const rendered_arg_list &args)
     {
       std::size_t total = fmt.size();
       for (std::size_t i = 0; i < args.size(); ++i)

include/vix/print/Print.hpp

@@ -219,6 +219,21 @@ namespace vix
       os << static_cast<std::underlying_type_t<E>>(e);
     }
 
+#ifdef _WIN32
+    inline constexpr const char *kBoxTopLeft = "+";
+    inline constexpr const char *kBoxTopRight = "+";
+    inline constexpr const char *kBoxBottomLeft = "+";
+    inline constexpr const char *kBoxBottomRight = "+";
+    inline constexpr const char *kBoxHorizontal = "-";
+    inline constexpr const char *kBoxVertical = "|";
+#else
+    inline constexpr const char *kBoxTopLeft = "\u250C";
+    inline constexpr const char *kBoxTopRight = "\u2510";
+    inline constexpr const char *kBoxBottomLeft = "\u2514";
+    inline constexpr const char *kBoxBottomRight = "\u2518";
+    inline constexpr const char *kBoxHorizontal = "\u2500";
+    inline constexpr const char *kBoxVertical = "\u2502";
+#endif
     // write_duration
     template <typename Rep, typename Period>
     void write_duration(std::ostream &os,
@@ -233,7 +248,11 @@ namespace vix
       }
       else if constexpr (std::is_same_v<Period, std::micro>)
       {
+#ifdef _WIN32
+        os << d.count() << "us";
+#else
         os << d.count() << "µs";
+#endif
       }
       else if constexpr (std::is_same_v<Period, std::milli>)
       {

src/config/Config.cpp

@@ -12,6 +12,7 @@
  */
 
 #include <vix/config/Config.hpp>
+#include <vix/utils/Env.hpp>
 
 #include <cstdlib>
 #include <fstream>
@@ -124,17 +125,17 @@ namespace vix::config
 
   std::string Config::getDbPasswordFromEnv()
   {
-    if (const char *value = std::getenv("VIX_DB_PASSWORD"); value && *value != '\0')
+    if (const char *value = vix::utils::vix_getenv("VIX_DB_PASSWORD"); value && *value != '\0')
     {
       return std::string(value);
     }
 
-    if (const char *value = std::getenv("DB_PASSWORD"); value && *value != '\0')
+    if (const char *value = vix::utils::vix_getenv("DB_PASSWORD"); value && *value != '\0')
     {
       return std::string(value);
     }
 
-    if (const char *value = std::getenv("MYSQL_PASSWORD"); value && *value != '\0')
+    if (const char *value = vix::utils::vix_getenv("MYSQL_PASSWORD"); value && *value != '\0')
     {
       return std::string(value);
     }