feat: ledger-gui — a read-only, live desktop view of the books

egui/wgpu app for owners and their accountant: Overview, Cash, Profit,
Transactions (with rendered receipts and journal history), Reports
(statements with interval columns, comparisons, drill-down), Accounts,
Documents, Company, Journal; Ctrl+K palette; back/forward; light/dark.
Follows the journal live (~30 ms from write to screen). --demo opens a
deterministic demo company, also used for screenshot tests.

Engine: ledger-store Snapshot (read-only, incremental, tolerant of a
half-written tail); ledger-core analysis (intervals, balance series,
P&L by interval, cash flows); ledger-config extracted from ledger-mcp
with the full company profile and cash_accounts.

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

crates/ledger-store/src/lib.rs

@@ -22,11 +22,13 @@ pub mod blob;
 pub mod error;
 pub mod journal;
 pub mod schema;
+pub mod snapshot;
 pub mod store;
 
 pub use blob::BlobStore;
 pub use error::StoreError;
 pub use journal::{GENESIS_PREV, JournalLine, JournalWriter};
+pub use snapshot::Snapshot;
 pub use store::{
     Attachment, DB_FILE, DepreciationRun, DisposalPreview, EntryRow, EventRow, JOURNAL_FILE,
     PayrollLineInput, Store,