perf: add Release build flags for binary size reduction

Add -fvisibility=hidden, -ffunction-sections, -fdata-sections,
-Wl,--gc-sections, -Wl,--strip-all, -Wl,--hash-style=gnu,
-Wl,--build-id=none to Release builds. Debug builds unchanged.
Release size-optimized binary: 523KB.

Author: Charliechen114514

cmake/compile/CompilerFlag.cmake

@@ -53,6 +53,20 @@ else()
     )
 endif()
 
+# Size-reduction flags for Release builds
+target_compile_options(cfbox_compiler_flags INTERFACE
+    $<$<CONFIG:Release>:-fvisibility=hidden>
+    $<$<CONFIG:Release>:-fvisibility-inlines-hidden>
+    $<$<CONFIG:Release>:-ffunction-sections>
+    $<$<CONFIG:Release>:-fdata-sections>
+)
+target_link_options(cfbox_compiler_flags INTERFACE
+    $<$<CONFIG:Release>:-Wl,--gc-sections>
+    $<$<CONFIG:Release>:-Wl,--strip-all>
+    $<$<CONFIG:Release>:-Wl,--hash-style=gnu>
+    $<$<CONFIG:Release>:-Wl,--build-id=none>
+)
+
 # ── Static linking ────────────────────────────────────────────
 if(CFBOX_STATIC_LINK)
     target_link_options(cfbox_compiler_flags INTERFACE -static)