P3: depreciation straight-line by days through the final month, schedules by day (defects 22, 9, D-37)

The final month takes what the months before leave, spread over its days;
a disposed asset stops on its disposal day. A skipped month is caught up
in the month the run is made; a reversed run un-posts its month. New
schedules spread by day; equal-months schedules must start on the 1st.
Amounts round to the currency's own minor unit. Kani and Lean proofs; an
exhaustive search over runs, reversals and disposals.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T3gXMVt7XJPi6ens1or9Dj

Cargo.lock

@@ -3867,10 +3867,12 @@ dependencies = [
  "chrono",
  "criterion",
  "jiff",
+ "ledger-store",
  "proptest",
  "rust_decimal",
  "serde",
  "serde_json",
+ "tempfile",
  "thiserror 2.0.21",
  "toml 1.1.8+spec-1.1.0",
 ]