Parties, attachment links, statements, reconciliations (store), TIN vault crate

Parties: one directory for vendors, contractors, customers, employees,
members, platforms, agencies, banks, landlords (ledger-core parties.rs).
W-9/W-4 facts without the number (last four only; any nine-digit run in a
party field is refused, Treas. Reg. 301.6109-4). Vendor and customer
records link to parties on replay; core tags every bill, invoice, payment,
and reversal with its counterparty. Journal events party.*,
entry.party_set; payroll lines name the employee party.

MCP: books.add_party, update_party, set_party_roles, set_w9, set_w4,
parties, party, set_entry_party; draft_entry party; run_payroll employee;
show party. Viewer: Parties directory and party pages, search, journal
text, W-9 attention, demo data.

One definition of a party's money (ledger_core::parties::activity) for
MCP and viewer. 1099 amounts count payments from cash and financing
accounts (a member paying for the company counts; a card doesn't; a
prepayment counts when made): vendor_1099_report_with, B-19.

Store: attachment links to any subject, statements, reconciliations
(schema v11), with replay and projection. ledger-vault: encrypted TIN and
W-9 records (ChaCha20-Poly1305, key file outside the books).

Spec-blind tests for parties (core, store, MCP, viewer) and attachments.

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

crates/ledger-core/src/payroll.rs

@@ -24,6 +24,10 @@ pub type PayrollRunId = u64;
 pub struct PayrollLine {
     /// Employee name, for the run record.
     pub employee_name: String,
+    /// The employee's party, if named (new runs should; runs from before
+    /// the party directory carry the name only).
+    #[serde(default)]
+    pub employee: Option<crate::PartyId>,
     /// Gross pay for the period.
     pub gross_pay: Decimal,
     /// Federal income tax withheld.
@@ -194,6 +198,7 @@ mod tests {
     fn line(name: &str) -> PayrollLine {
         PayrollLine {
             employee_name: name.to_string(),
+            employee: None,
             gross_pay: d(500_000),          // 5000.00
             federal_withholding: d(75_000), // 750.00
             state_withholding: d(25_000),   // 250.00