Inconsistent scope defaults: rtk discover (project) vs rtk gain (global)

Problem

rtk discover and rtk gain have inconsistent scope defaults AND the --all flag means different things on each:

Command	Default scope	--all means
rtk discover	current project	scan all projects
rtk gain	global (all projects)	show all time breakdowns (daily + weekly + monthly)

So --all means "widen scope" on discover but "widen time range" on gain. Running both commands to understand RTK coverage requires opposite flags for scope, and --all is a footgun that does something unexpected on gain.

Expected

1. Consistent scope defaults — both should default to global (more useful), with --project to narrow
2. Consistent --all semantics — or avoid reusing --all for unrelated purposes across commands

Suggested fix

• rtk discover: default to global, add --project flag to narrow (matching rtk gain)
• Rename rtk gain --all to something like --full or --breakdown to avoid the semantic collision