kc_format.py:
- Auto-create silo/manifest.json with default fields (UUID, timestamps,
username) when saving a .kc file that lacks one
- Update modified_at timestamp on each save
- KC_VERSION = 1.0
Platform integration:
- kindred-create.desktop: add application/x-kindred-create MIME type
- kindred-create.xml: register .kc glob patterns with dedicated MIME type
(application/x-kindred-create), separate from .fcstd type