feat(iif): carry each line's project in CLASS, the classes declared first

The P3 cutover review's open point 1: entries carry projects (classes,
B-37), but the QuickBooks Desktop file (B-34) left the CLASS field empty
on every line, and neither B-34 nor the README said so, though B-34 rule
6 says nothing changes silently.

Intuit's IIF Import Kit (vendored in docs/spec/sources/intuit-iif.md,
the kit's SHA-256 unchanged): the `!CLASS` header help says "Only the
NAME column is required" and a subclass's NAME is its parents' names
first, joined by colons; the kit's "Import First - List Declarations"
example declares `!CLASS` rows before any transaction, and its "2004
Deposit (Income)" example names the class line by line in CLASS. So the
file now declares every class in a `!CLASS` list after the accounts and
before `!TRNS`, and writes each line's class in CLASS (empty where the
line has none). Books with no class write no list, byte for byte as
before. A line whose class wasn't declared is refused
(IifError::UndeclaredClass), never written classless.

A class's NAME follows B-34's rules for an account's own name: plain
ASCII (rule 3), a colon written '-' (it would start a subclass),
trimmed, '?' if nothing is left, cut to 31 characters: Intuit's qbXML
Onscreen Reference gives `ClassAdd`'s Name "maxDT" : 31 (and 31 in the
Canadian, UK and Australian desktop editions; 100 only in Online), the
same as its `AccountAdd` Name (both JSON files vendored by SHA-256);
Conductor's QuickBooks Desktop API reference agrees and says the name is
case-insensitive. Classes whose NAMEs would match ignoring case get
" (id)", round after round, as accounts get " (code)", except that
among names that match, those already written differently from the
books (made safe, or tagged) yield first, a second " (id)" if need be:
a class's own name is kept unless another class's own name is the same
ignoring case (classes 1 "Café", 2 "Cafe", 3 "Cafe (1)" are written
"Cafe (1) (1)", "Cafe", "Cafe (1)"). Each class is tagged twice at most
and ids differ, so none is left alike (a hand-built list is refused). Each class name
written differently is an IifChange (IifField::ClassName), said one
line each in the warnings and in the package README, whose
"written differently" paragraph now names class names' limits; its IIF
line says CLASS is each line's project when there are classes. The MCP
and viewer notes count "account or class name(s)".

API: `iif_classes(ledger)` builds the list; `journal_to_iif` takes it
(`&[]` for none).

Docs: rules.md B-34 rule 8 with its sources; intuit-iif.md (the
`!CLASS` help, the list declarations and deposit examples, Intuit's SDK
department page, the qbXML Onscreen Reference's ClassAdd and AccountAdd
and Conductor's class reference, each with SHA-256);
mcp-interface.md (books.export iif, the package note); the bookspec
example iif-quickbooks-journal-file.toml (two projects: one carried and
renamed, one only declared; every line derived by hand); testing.md;
STATUS (open point 1 done; point 3 waits for the close, the owner said).

Tests: ledger-import
`iif_writes_each_lines_class_and_declares_the_classes_first`,
`iif_class_names_fit_quickbooks_and_every_change_is_listed`,
`iif_class_names_written_as_the_books_have_them_are_kept`,
`iif_refuses_an_undeclared_or_unfit_class`, property
`iif_class_names_never_clash`; ledger-package
`the_package_iif_carries_each_lines_project` and the bookspec example.
Broken to confirm: CLASS written empty fails the two exact-file tests,
the package test and the bookspec example; the " (id)" tag dropped fails
the names test and the property; tagging every name that meets (no
yielding) fails the kept-names test and the property (its shrunk case,
"A-B" beside "A\uFF1AB", kept in the regressions file).

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

crates/ledger-package/src/iif.rs

@@ -18,6 +18,8 @@
 //!      closing entries (it works out retained earnings itself), so an
 //!      imported close would zero its period's profit. The file's
 //!      balances are the trial balance as of as_of without the closes.
+//!   3. Every class (project) in the books is declared, and each line
+//!      carries its class (rules.md B-34 rule 8).
 //! ```
 
 use chrono::NaiveDate;
@@ -29,14 +31,15 @@ use ledger_core::{AccountId, AccountType, Ledger};
 /// payable control accounts AR and AP, the cost and accumulated
 /// depreciation accounts of an asset bought by `as_of` FIXASSET, and the
 /// rest follow their wanderbooks type (other current asset, other current
-/// liability, equity, income, expense). Returns the file and every text it
-/// writes differently from the books.
+/// liability, equity, income, expense), and every class with each line's
+/// class in CLASS. Returns the file and every text it writes differently
+/// from the books.
 pub fn export_iif(
     ledger: &Ledger,
     cash_codes: &[String],
     as_of: NaiveDate,
 ) -> Result<ledger_import::Iif, String> {
-    use ledger_import::{QbAccountType as Qb, iif_accounts, journal_to_iif};
+    use ledger_import::{QbAccountType as Qb, iif_accounts, iif_classes, journal_to_iif};
     let fixed: std::collections::HashSet<AccountId> = ledger
         .registered_assets()
         .filter(|a| ledger.asset_acquired_date(a.id).is_some_and(|d| d <= as_of))
@@ -68,5 +71,5 @@ pub fn export_iif(
         .posted_entries()
         .filter(|e| e.date() <= as_of && !closes.contains(&e.id()))
         .collect();
-    journal_to_iif(&accounts, &entries).map_err(|e| e.to_string())
+    journal_to_iif(&accounts, &iif_classes(ledger), &entries).map_err(|e| e.to_string())
 }

crates/ledger-package/src/package.rs

@@ -576,7 +576,12 @@ pub fn build_package<B: PackageBooks + ?Sized>(
         },
         iif = {
             let mut t = format!(
-                "general-journal.iif: every posted entry from the first through {as_of_s}, for import into QuickBooks Desktop. Plain ASCII text (its import turns anything else into \"?\"), CR LF line endings; DOCNUM is each entry's id in these books. Period-closing entries are left out: QuickBooks keeps none and works out retained earnings itself, so an imported close would zero its period's profit; trial-balance includes them{}.\n",
+                "general-journal.iif: every posted entry from the first through {as_of_s}, for import into QuickBooks Desktop. Plain ASCII text (its import turns anything else into \"?\"), CR LF line endings; DOCNUM is each entry's id in these books{}. Period-closing entries are left out: QuickBooks keeps none and works out retained earnings itself, so an imported close would zero its period's profit; trial-balance includes them{}.\n",
+                if ledger.list_classes().is_empty() {
+                    ""
+                } else {
+                    "; CLASS is each line's project, the projects declared first as QuickBooks classes"
+                },
                 if company.members.is_empty() {
                     ""
                 } else {
@@ -592,9 +597,10 @@ pub fn build_package<B: PackageBooks + ?Sized>(
             }
             if !warnings.is_empty() {
                 t.push_str(&format!(
-                    "Written differently in general-journal.iif to fit QuickBooks Desktop (plain ASCII; account names at most {} characters a level, no two alike; a subaccount of another QuickBooks type than its parent's at the top level; account numbers at most {} characters, no two alike; memos at most {} characters); every other file keeps the books' text:\n",
+                    "Written differently in general-journal.iif to fit QuickBooks Desktop (plain ASCII; account names at most {} characters a level, no two alike; a subaccount of another QuickBooks type than its parent's at the top level; account numbers at most {} characters, no two alike; class (project) names at most {} characters, no two alike; memos at most {} characters); every other file keeps the books' text:\n",
                     ledger_import::NAME_MAX,
                     ledger_import::NUMBER_MAX,
+                    ledger_import::NAME_MAX,
                     ledger_import::MEMO_MAX
                 ));
                 for w in &warnings {