* Refactor bastardkb/scylla
- Update keyboard aliases accordingly
- Migrate keymap to JSON and better represent physical layout
- scylla/blackpill
- Migrate common configuration to keyboard level
- Remove unnecessary or user-specific configuration
- Migrate some configuration to data-driven
- Use short SPDX license headers
- Remove unnecessary rules.mk file
- Formatting pass on keyboard.json
- scylla/v1
- Remove likely unneeded version, per qmk#23814
- scylla/v2
- Remove splinky_2 revision, per qmk#23814
- Remove splinky_3, stemcell revisions; converter feature should
be used here
- Rename scylla/v2/elitec -> scylla/promicro, as a converter can
be used for any pin-compatible microcontrollers
* Small keymap fix
