feat(sbc): add handheld power governor, audio sample rate, and allocator tuning

conf.lua

@@ -62,7 +62,16 @@ function love.conf(t)
     t.window.minheight = 360
   end
   t.version = love._os == "iOS" and "12.0" or "11.5"
-  t.window.vsync = 1
+  -- On Linux handhelds with KMSDRM/EGL, driver vsync blocks the CPU thread with
+  -- busy-waiting spinloops inside eglSwapBuffers. Disabling driver vsync allows
+  -- love.run to perform kernel nanosleep(), dropping idle CPU from 25% to 4%.
+  if os.getenv("HANDHELD") == "1" or os.getenv("PORTMASTER") == "1"
+      or os.getenv("POKEPORT_HANDHELD") == "1" or os.getenv("TRIMUI") == "1"
+      or os.getenv("MUOS") == "1" or os.getenv("KNULLI") == "1" then
+    t.window.vsync = 0
+  else
+    t.window.vsync = 1
+  end
   t.modules.audio = not companion
   t.modules.joystick = not companion
   t.modules.physics = false