Promote COST_EQ_TOLERANCE from a function-local const to a module-level
constant in sidebar.rs.
Add SessionCostSnapshot::total_usd() and total_cny() helpers that
encapsulate session+subagent cost summation, used during session restore.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
# Conflicts:
# crates/tui/src/session_manager.rs
# crates/tui/src/tui/sidebar.rs
# crates/tui/src/tui/ui.rs
lbcheng
9f2b8a5f14