fix: period close sweeps only through the period end; partnerships close into members' capital

The close zeroed every revenue and expense account's all-time movement,
so closing a period after later entries were posted swept those too:
close January in March and February's and March's income landed in
January's closing entry. The preview had the same bug and never showed
where the net went. Now:

- close_period_to(id, to) zeroes balances as of the period end; entries
  dated later stay open for their own period. Periods must close in
  order (LedgerError::CloseOutOfOrder): a later close has already swept
  the earlier period.
- CloseTo::Members: for a partnership (multi-member LLC) the net goes to
  each member's capital account by share, to the cent, the last member
  absorbing rounding, which is what K-1 capital accounts track.
  CloseTo::RetainedEarnings (3999) stays the default; close_period is
  shorthand for it. books.close_period picks Members when
  wanderbooks.toml lists members.
- The journal records the close target; replay re-derives the closing
  entry and now compares every line with the journal, not just the id,
  so a change to closing math can never silently rewrite history.
- The tool's preview is the real close run on a clone of the ledger
  (Ledger now derives Clone), so preview and post can't disagree.
- Members' equity: closing entries into a capital account are income,
  not contributions. Balance sheet for a partnership: capital accounts
  (with allocated earnings), then only unallocated earnings —
  "Undistributed earnings, prior years" if any, and this year's unclosed
  net income (loss). periods::allocate is shared by the close and the
  statement.

Tests: January closed after February is posted sweeps exactly Dr 4000
2,500 / Cr 6100 800 / Cr 3999 1,700 (mutation-checked: the old code gives
3,500/120/800/2,580); out-of-order close refused; a partnership close
splits 666.67 into 333.34/333.33 with no 3999, and the members' equity
statement reads correctly before and after; store replay of a members
close (reopen, rebuild, verify); partnership and corporate balance sheet
layouts; stdio close preview equals the posted lines.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MtYEaR6M6Ybdhm6X98BWNu

crates/ledger-mcp/tests/mcp_stdio.rs

@@ -1022,4 +1022,37 @@ fn mcp_period_statements_over_stdio() {
         json!({"format": "pdf", "report": "members_equity", "end": "2026-02-28"}),
     );
     assert_eq!(pdf["content_encoding"], "base64");
+
+    // Closing January: a one-member LLC closes into the member's capital
+    // account, not Retained Earnings. The preview is exactly what posts.
+    let jan = mcp.call(
+        "books.create_period",
+        json!({"name": "2026-01", "start": "2026-01-01", "end": "2026-01-31"}),
+    );
+    let jan_id = jan["period_id"].as_u64().unwrap();
+    let preview = mcp.call(
+        "books.close_period",
+        json!({"period_id": jan_id, "confirmed": false}),
+    );
+    assert_eq!(
+        preview["lines"],
+        json!(["Debit 4000 4.00", "Credit 3000 4.00"])
+    );
+    let closed = mcp.call(
+        "books.close_period",
+        json!({"period_id": jan_id, "confirmed": true}),
+    );
+    assert_eq!(closed["lines"], preview["lines"]);
+    let jan_bs = mcp.call("books.balance_sheet", json!({"as_of": "2026-01-31"}));
+    assert_eq!(jan_bs["equity_accounts"][0]["amount"], "1004.00");
+    assert_eq!(jan_bs["current_earnings"], "0.00");
+    // The close is income, not a contribution.
+    let me = mcp.call(
+        "books.export",
+        json!({"format": "json", "report": "members_equity", "start": "2026-01-01", "end": "2026-01-31"}),
+    );
+    let me: serde_json::Value = serde_json::from_str(me["content"].as_str().unwrap()).unwrap();
+    assert_eq!(me["total"]["contributions"], "1000.00");
+    assert_eq!(me["total"]["net_income"], "4.00");
+    assert_eq!(me["total"]["ending"], "1004.00");
 }