- RuleUsage + UsageLedger: per-rule, per-day minutes/opens in app-group
defaults (monotonic minutes, incrementing opens, midnight rollover by
day-keying); MockUsageLedger for tests and seeded UI scenarios
- usage-aware status: a limit rule whose daily budget is spent on an
enabled day is active (blocking) until next midnight; Hard Mode gating
and app-list locking honor it; soft unblock pauses until midnight
- RuleEnforcer shields spent limit rules (always Block mode) while the
app runs
- new Usage section under Blocked Apps: '18m of 45m used today · 27m
left', '2 of 5 opens today · 3 opens left', 'Blocked until tomorrow'
- new 'limits' seed scenario + UI tests
