docs: improve migration docs

docs: simplify quickstart

fix: db_migration should not create bootstrap_version

Determine the server_role after the migration is done.

ci: ignore scratch directory

ci: ignore scratch directory

docs: update model catalog (#3463)

fix: downgrade xformers to 0.0.30 for compatibility with NVIDIA 5090 …

…GPUs

fix: downgrade xformers to 0.0.30 for compatibility with NVIDIA 5090 …

…GPUs

docs: Add guidance for skipping compatibility architecture checks wit…

…h custom backend versions

docs: corrections and additions

Signed-off-by: linyinli <yinlin@gpustack.ai>