V2.0.4 Bugfix

[bustesoul]

Summary

• Fix local save:/... scene path handling on Windows Local scenes fail to load with os error 123 #23
• Fix Hub scan package/version parsing and download candidate matching Hub Scan Missing and Scan Updates not Works #22
• Harden backend path and filename handling to prevent unsafe path joins
• Bump version to 2.0.4

Upgrade Notes

• No migration is required for existing user data, databases, or .var packages
• This release does not delete, move, or rewrite existing user .var files
• Path validation is stricter: malformed historical records or inputs containing ../, drive prefixes, colons, or path separators may now be skipped or rejected

Verification

• cargo +stable test -- --test-threads=1
• cargo +stable check