feat: more granular control of flag inheritance

[mfridman]

Command flags can be inherited by child commands, but this needs careful handling. Some flags should only affect the root command, while others are useful globally:

• --version should be root-only since version information applies to the whole program and probably only the root Exec function actually handles this flag
• --verbose should be inherited since logging verbosity affects most commands

We might want to consider extending FlagMetadata to specify inheritance behavior per flag.