Split --help "Flags:" into command-specific and common flags

[BlueLabelscotch]

Summary

• --help on a leaf command (e.g. harness list project) currently dumps every flag into one Flags: block — mixing the command's own flags with framework-level flags that are mechanically the same across every command sharing its verb (--format, --json, --columns, --all, --limit, etc). This makes it harder to scan for humans and costly for AI agents that have to read past a large block of repeated boilerplate to find what's actually specific to the command.
• Adds a custom Cobra usage template (pkg/rootcmd/usage.go) that splits the existing Flags: section into two: Flags: (command-specific) and Common Flags: (built-in verb/endpoint flags), leaving Global Flags: untouched.
• Purely a --help rendering change: no flags are hidden, no flag registration/parsing/completion behavior changes.

Future Work

• we can hide the common verbs and global flags behind a generic command like list --help , but this has some tradeoffs and problem with verb specific and conditional flags.