Fixed assets, fully featured: tags, serials, acquisition links, label sheets, the fixed asset register, and an Assets section in the viewer; fix a flaky verify

- core: asset tags (generated PREFIX-0001 or the human's own; unique ignoring case; never reused by another asset) and serial numbers (rules.md B-24); a journaled link from an asset to the entry that acquired it (posted, unreversed, debiting the cost account); fixed_asset_register(as_of), reconciled to the GL (unposted depreciation, unregistered cost)
- store: asset.tagged, asset.serial_set, asset.acquisition_linked journaled, replayed, projected (schema v9); differs_from now also compares control roles and tag history
- config: [books] asset_tag_prefix, default the company's initials without legal-form words
- import: Avery 5160/8160 label sheets with QR codes (geometry vendored from Avery, docs/spec/sources/avery-5160.md); the register as XLSX and PDF
- mcp: register_asset tags (and links) automatically; books.label_asset, books.asset_labels; asset tools take a tag; books.show asset / assets page / register report; export fixed_asset_register (json, csv, xlsx, pdf) and in the CPA package
- viewer: Assets page (register, reconciliation), asset page (identity, schedule posted vs not, entries, documents), Fixed asset register report, global search by tag/serial/description, journal text, needs-attention items
- fix: verify compared snapshot amounts as strings; a zero total summed in hash-map order could print "0" or "0.00", so agreeing books failed verify at random. Now by value (regression test)
- tests: spec-blind suites for tags, register, prefix, store, MCP; label and register PDF/XLSX tests; viewer tests

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

crates/ledger-store/src/viewer.rs

@@ -16,7 +16,7 @@ use std::path::{Path, PathBuf};
 #[serde(tag = "show", rename_all = "snake_case")]
 pub enum ViewerTarget {
     /// A top-level page: overview, cash, profit, transactions, reports,
-    /// accounts, documents, company, journal.
+    /// accounts, assets, documents, company, journal.
     Page {
         /// Page name.
         page: String,
@@ -39,7 +39,7 @@ pub enum ViewerTarget {
     Report {
         /// profit_and_loss, balance_sheet, cash_flow, members_equity,
         /// trial_balance, general_ledger, tax_summary, vendor_1099,
-        /// ar_aging, ap_aging.
+        /// ar_aging, ap_aging, fixed_asset_register.
         report: String,
         /// First date, YYYY-MM-DD.
         start: Option<String>,
@@ -57,6 +57,11 @@ pub enum ViewerTarget {
         /// Attachment id.
         attachment_id: u64,
     },
+    /// One fixed asset: its identity, schedule, entries, and documents.
+    Asset {
+        /// Asset id.
+        asset_id: u64,
+    },
     /// The transactions list, searched.
     Search {
         /// Search text: description, account, vendor, amount.