Migrate build target markers to keyboard.json - 0AB (#23488)

keyboards/1k/keyboard.json

@@ -8,6 +8,16 @@
     "pid": "0x0001",
     "device_version": "0.0.1"
   },
+  "processor": "attiny85",
+  "bootloader": "custom",
+  "build": {
+    "lto": true
+  },
+  "features": {
+    "grave_esc": false,
+    "magic": false,
+    "space_cadet": false
+  },
   "rgblight": {
     "led_count": 1
   },

keyboards/1k/rules.mk

@@ -1,26 +1,2 @@
-# MCU name
-MCU = attiny85
-
-# Bootloader selection
-BOOTLOADER = custom
 BOOTLOADER_SIZE = 1862
 PROGRAM_CMD = micronucleus --run $(BUILD_DIR)/$(TARGET).hex
-
-# Build Options
-#   change yes to no to disable
-#
-BOOTMAGIC_ENABLE = no       # Enable Bootmagic Lite
-MOUSEKEY_ENABLE = no        # Mouse keys
-EXTRAKEY_ENABLE = no        # Audio control and System control
-CONSOLE_ENABLE = no         # Console for debug
-COMMAND_ENABLE = no         # Commands for debug and configuration
-NKRO_ENABLE = no            # Enable N-Key Rollover
-BACKLIGHT_ENABLE = no       # Enable keyboard backlight functionality
-RGBLIGHT_ENABLE = no        # Enable keyboard RGB underglow
-AUDIO_ENABLE = no           # Audio output
-
-# Save as much space as we can...
-LTO_ENABLE = yes
-GRAVE_ESC_ENABLE = no
-MAGIC_ENABLE = no
-SPACE_CADET_ENABLE = no