fix(curator): default cycle is every 7 days, not 24 hours

Weekly is closer to how skill churn actually works — most agent-created
skills don't change multiple times per day, so a daily review is pure
cost without benefit. Bumping the default to 7 days reduces aux-model
spend while still catching drift and staleness on the timescales that
matter (30d stale, 90d archive).

Changes:
- DEFAULT_INTERVAL_HOURS: 24 -> 168 (7 days)
- config.yaml default: interval_hours: 24 -> 24 * 7
- CLI status line renders as '7d' when interval is a whole-day multiple
- Test `test_old_run_eligible` decoupled from the exact default: it now
  uses 2 * get_interval_hours() so future tweaks don't break it

hermes_cli/config.py

@@ -927,8 +927,8 @@ DEFAULT_CONFIG = {
     # See `hermes curator status` for the last run summary.
     "curator": {
         "enabled": True,
-        # How long to wait between curator runs (hours).
-        "interval_hours": 24,
+        # How long to wait between curator runs (hours).  Default: 7 days.
+        "interval_hours": 24 * 7,
         # Only run when the agent has been idle at least this long (hours).
         "min_idle_hours": 2,
         # Mark a skill as "stale" after this many days without use.