[Keyboard] Add Foundation to QMK (#17573)

* add mechlovin foundation keyboard

Co-authored-by: Drashna Jaelre <drashna@live.com>

keyboards/mechlovin/foundation/rules.mk

@@ -0,0 +1,21 @@
+# MCU name
+MCU = STM32F103
+BOARD = STM32_F103_STM32DUINO
+
+# Bootloader selection
+BOOTLOADER = stm32duino
+
+# Build Options
+#   change yes to no to disable
+#
+BOOTMAGIC_ENABLE = yes      # Enable Bootmagic Lite
+MOUSEKEY_ENABLE = yes       # Mouse keys
+EXTRAKEY_ENABLE = yes       # Audio control and System control
+CONSOLE_ENABLE = yes        # Console for debug
+COMMAND_ENABLE = yes        # Commands for debug and configuration
+NKRO_ENABLE = yes           # Enable N-Key Rollover
+BACKLIGHT_ENABLE = no       # Enable keyboard backlight functionality
+RGBLIGHT_ENABLE = yes       # Enable keyboard RGB underglow
+ENCODER_ENABLE = yes
+AUDIO_ENABLE = no           # Audio output
+ENCODER_MAP_ENABLE = yes