Fixed assets carry federal tax basis beside book value; tests sweep stale temp dirs

- core: TaxBasisRule (cost IRC 1012, carryover IRC 723, personal-use conversion Treas. Reg. 1.168(i)-4(b)), TaxBasis with the contributor's adjusted basis, Asset::tax_basis and ::built_in_gain (IRC 704(c)); the register gains tax rule, contributor basis, tax basis, built-in gain, total tax basis, missing count (rules.md B-25; sources vendored in docs/spec/sources/irs-partnership-basis.md)
- store: asset.tax_basis_set journaled, replayed, projected (schema v10)
- mcp: books.set_asset_tax_basis; register_asset takes tax_basis_rule and contributor_basis, checked before anything registers (found by the spec-blind suite); list_assets and the register export (json, csv) carry tax basis; instructions say to record it for every asset
- import: the register's XLSX and PDF gain the federal tax basis table with citations
- viewer: tax basis on the Assets page, the asset page (a Tax basis card), the report, the journal, and Needs attention for assets without one
- just: check and the mutation recipes sweep this user's test book dirs older than an hour (killed runs had left 23 GB in RAM-backed /tmp)
- docs: the parties, attachments, TIN vault, completeness engine, and updates designs (docs/parties-and-attachments.md)
- tests: spec-blind tax basis suites in core, store, MCP; register PDF/XLSX and viewer tests

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

docs/spec/README.md

@@ -13,7 +13,7 @@ layers differ in what they cover and in whether we may copy them:
 | Layer | What it governs | Copyright | Here |
 |---|---|---|---|
 | **Pacioli (1494), Geijsbeek translation (1914)** | The mechanics of double entry: debits equal credits, the trial balance, one money, writing only forward, correcting by opposite entry, closing into capital. No modern standard restates these; they predate every regulator. | Public domain | Vendored verbatim: `sources/pacioli-1494.md` |
-| **IRS: Internal Revenue Code, Treasury Regulations, publications, form instructions** | Records and supporting documents, retention, accounting periods and methods, information returns (1099), capitalization (de minimis, 12-month rule), partners' capital, payroll taxes, rounding on returns, return line items for tax categories (`sources/irs-tax-lines.md`) | Public domain (17 U.S.C. §105; IRS.gov's content policy) | Vendored verbatim: `sources/irs-*.md`, `sources/us-public-domain-status.md` |
+| **IRS: Internal Revenue Code, Treasury Regulations, publications, form instructions** | Records and supporting documents, retention, accounting periods and methods, information returns (1099), capitalization (de minimis, 12-month rule), partners' capital, tax basis of purchased and contributed property (`sources/irs-partnership-basis.md`), payroll taxes, rounding on returns, return line items for tax categories (`sources/irs-tax-lines.md`) | Public domain (17 U.S.C. §105; IRS.gov's content policy) | Vendored verbatim: `sources/irs-*.md`, `sources/us-public-domain-status.md` |
 | **File formats: Intuit (QuickBooks Online bank CSV, QuickBooks Desktop IIF), ECMA-376 Office Open XML, Microsoft Excel limits, Avery label sheets** | What `ledger-import` reads and writes: bank/card CSV layouts and signs, IIF journal entries, how XLSX stores numbers and Excel's 15-digit precision, asset-label sheet geometry (Avery 5160) | © Intuit Inc.; © Ecma International; © Microsoft; © Avery Products Corporation | Cited with short quotes, URLs, and hashes: `sources/intuit-bank-csv.md`, `sources/intuit-iif.md`, `sources/xlsx-numbers.md`, `sources/avery-5160.md` |
 | **FASB Accounting Standards Codification (ASC)** | Authoritative US GAAP: cash flows (ASC 230), revenue and principal vs agent (ASC 606), foreign currency (ASC 830), credit losses and aging (ASC 326), property and depreciation (ASC 360) | © Financial Accounting Foundation | Cited by paragraph with short quotes only (in `rules.md`) |
 | **FASB Concepts Statement No. 8, Chapter 4 (2021)** | Definitions of the five elements (it replaced Concepts Statement 6) | © Financial Accounting Foundation; non-authoritative | Cited with short quotes only |