tax summary: Schedule K items stated separately; XLSX never shows a wrong amount

From the IRS form instructions (now quoted in docs/spec/sources/
irs-tax-lines.md):
- On Forms 1065 and 1120-S, Schedule K takes "only taxable portfolio
  interest", and charitable contributions are among the items the entity
  "must state separately". The tax summary counted both in ordinary
  income and deductions; they now go in TaxSummary::separately_stated,
  outside book_net and tax_net, and the report, MCP export, and viewer
  list them under "Separately stated to owners (Schedule K)".
- Schedule C: "Do not include charitable contributions". The category no
  longer applies to Schedule C (a sole proprietor's gift is personal, an
  owner draw).
- interest_income's note: interest earned in the business itself is
  ordinary income (other_income).

XLSX: a cell number is a binary double and Excel honors 15 significant
digits (Microsoft, "Excel specifications and limits"), so an amount over
$9,999,999,999,999.99 or finer than a cent is written as its exact text,
right-aligned, instead of a number Excel would show wrong. The old
conversion also fell back to 0.0 silently; gone. Property test: every
whole-cent amount up to 15 digits round-trips exactly.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GWVo7x3UHw5kwCUaWxiejX

crates/ledger-mcp/src/server.rs

@@ -3994,6 +3994,7 @@ impl BooksServer {
                 "income": ts.income.iter().map(line).collect::<Vec<_>>(),
                 "cost_of_goods": ts.cost_of_goods.iter().map(line).collect::<Vec<_>>(),
                 "deductions": ts.deductions.iter().map(line).collect::<Vec<_>>(),
+                "separately_stated": ts.separately_stated.iter().map(line).collect::<Vec<_>>(),
                 "uncategorized": ts.uncategorized.iter().map(|u| serde_json::json!({
                     "account": u.account, "book": money(u.book),
                 })).collect::<Vec<_>>(),
@@ -4007,6 +4008,7 @@ impl BooksServer {
             ("income", &ts.income),
             ("cost_of_goods", &ts.cost_of_goods),
             ("deductions", &ts.deductions),
+            ("separately_stated", &ts.separately_stated),
         ] {
             for l in lines {
                 csv.push_str(&format!(