Ports the two pieces of Shipyard's lane-gc.sh that match CCAM's actual
architecture: kill Playwright MCP processes reparented to pid 1 (owning
session died), cap hook logs over 10MB back to their last 2MB in place.
Drops auto-removing stale worktrees by age (conflicts with the
never-automatic-destroy rule), state archiving, and scratch-debris
sweep (different storage architecture / files CCAM doesn't generate) —
see docs/superpowers/specs/2026-08-05-lane-gc-design.md.
