[MAJOR] Update COSMIC API access, add createdb command, improve tests/docs, and remove unused sync

[apeltzer]

Hello!

this fixes a few issues with

• Update COSMIC database API access to use the current endpoint
• Fix file parsing to handle input formats correctly
• Improve integration tests: minimal tests run on every PR; COSMIC tests run when credentials are available but are skipped on forks to avoid spurious failures
• Add createdb command for building databases from local files, bypassing download URLs entirely — as long as you have the raw COSMIC/Mitelman/FusionGDB2 files, you're good (resolves intermittent URL/download issues)
• Expand documentation
• Remove the unused sync command (Remove sync #69)

Checklist

• Specify in detail the change
• Make sure to follow guidelines in docs when adding database/tool
• Documentation in docs is updated
• CHANGELOG.md is updated
• README is updated

This version is a

Add LEVEL in parenthesis to the commit message

• MAJOR - when you make incompatible API changes
• MINOR - when you add functionality in a backwards compatible manner
• PATCH - when you make backwards compatible bug fixes or documentation/instructions

[apeltzer]

@clingen-sthlm maybe ;-)

[rannick]

Great work, sorry for the late approval