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

crates/ledger-gui/src/demo.rs

@@ -539,6 +539,9 @@ pub fn build(dir: &Path, today: NaiveDate) -> Result<(), StoreError> {
         months: 12,
         balance_account: prepaid,
         pl_account: insurance,
+        // A new schedule spreads by the day (D-11, D-37): a small first
+        // and last month around eleven full ones.
+        convention: ledger_core::ScheduleConvention::Daily,
     })?;
 
     let mut open_invoices: Vec<(u64, NaiveDate, Decimal)> = Vec::new();