Projects: classes as entities, and the sidebar fits short windows

A project is a class with facts (description, status, kind, party,
dates, links, notes) in one project.set event behind the format
feature projects. Four tools (books.add_project, update_project,
projects, project); documents and decisions link to projects; B-37:
on-spec costs are expensed as incurred, repayment is revenue, and the
unrecovered cost is never below zero (Kani). Viewer: a Projects list
and a project page with its figures, by month and by account. The
sidebar measures its footer instead of reserving a fixed 172 px.

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

crates/ledger-store/src/ops.rs

@@ -63,7 +63,7 @@ pub fn report_columns(
 #[serde(tag = "show", rename_all = "snake_case")]
 pub enum ViewerTarget {
     /// A top-level page: overview, cash, profit, transactions, reports,
-    /// accounts, assets, parties, documents, company, journal.
+    /// accounts, assets, parties, projects, documents, company, journal.
     Page {
         /// Page name.
         page: String,
@@ -120,6 +120,12 @@ pub enum ViewerTarget {
         /// Party id.
         party_id: u64,
     },
+    /// One project (a class with its facts): its figures, entries,
+    /// documents and decisions.
+    Project {
+        /// Class id.
+        class_id: u32,
+    },
     /// One reconciliation: its account, with the account's statements and
     /// reconciliations.
     Reconciliation {