Add VIA support for MeowyPad by silly group

[stwupid]

Description

Adds VIA support for MeowyPad - a 3x3 macropad with OLED display by silly group.

Hardware:

• Controller: Seeed XIAO RP2040
• Layout: 3x3 matrix (COL2ROW)
• Features: SSD1306 OLED display
• Vendor ID: 0x5347 (SG)
• Product ID: 0x3301

VIA Definition:

• Location: v3/silly_group/meowy_pad/meowy_pad.json
• Matrix: 3 rows × 3 columns
• 4 layers supported

QMK Pull Request

qmk/qmk_firmware#25991

VIA Keymap Pull Request

VIA keymap is included in the QMK PR above at keyboards/silly_group/meowy_pad/keymaps/via/

Checklist

• The VIA support for this keyboard is MERGED in QMK master already (MANDATORY) - PR pending review
• VIA keymap is MERGED in VIA userspace master already (MANDATORY) - Included in QMK PR
• The VIA definition follows the guide here: https://caniusevia.com/docs/layouts
• I have a V3 JSON version for this keyboard definition.(MANDATORY)
• I have formatted the JSON file to have consistent formatting with the rest of the repository.
• I have tested this keyboard definition using VIA's "Design" tab.
• I have tested this keyboard definition with firmware on a device. - Testing in progress
• I have assigned alpha keys and modifier keys with the correct colors.
• The Vendor ID is not 0xFEED