Add silly_group/meowy_pad

[stwupid]

Description

Adds support for MeowyPad by silly group - a 3x3 macropad with SSD1306 OLED display (0.96").

Hardware:

• Controller: Seeed XIAO RP2040
• Layout: 3x3 matrix (COL2ROW)
• Features: SSD1306 OLED display connected to D6/D7 (GP6/GP7)
• VID: 0x5347 (SG - silly group)
• PID: 0x3301

Keymaps:

• default: Basic QWERTY layout (Q/W/E, A/S/D, Z/X/C)
• via: VIA-enabled with 4 layers for full customization

OLED Implementation:

• Displays keyboard name and manufacturer
• Shows current layer number
• Connected via I2C (GP6=SDA, GP7=SCL)

Types of Changes

• Keyboard (addition or update)

Issues Fixed or Closed by This PR

• N/A - new keyboard addition

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

Additional Notes

VIA support PR: the-via/keyboards#2520

[drashna]

This should be removed.

[drashna]

This can can and should be removed.