fix: hide XBRL hypercube scaffolding rows (Table / Line Items)

[jfrench9]

Summary

Follow-up to #17. Stripping the XBRL role tags from labels (0.2.8) exposed that us-gaap:StatementTable and us-gaap:StatementLineItems render as bare, duplicated "Statement" header rows in the statement body — visible in both the file/holon route and the SEC route (AAPL 10-K and 10-Q). These are pure hypercube plumbing: the [Table] is the hypercube itself and [Line Items] is its container; neither carries facts, and neither is a meaningful heading.

Change

• In the shared buildPivot row walk, skip emitting a header row for abstract concepts whose local name ends in Table or LineItems, and keep their children at the current depth so the tree doesn't over-indent.
• The check keys off the concept's local name, which is identical whether elements are keyed by IRI (store/holon route) or qname (SEC route) — so both rendering routes hide the plumbing the same way, via one change at the shared choke point.
• [Axis] / [Domain] / [Member] / [Abstract] / [Roll Forward] rows are untouched — those carry real names/data.

Before → after (AAPL income statement)

INCOME STATEMENT              INCOME STATEMENT
    STATEMENT          →          Product
        STATEMENT                 Service
            Product               ...
            Service

Verification

• New buildPivot tests (qname-keyed, mirroring the SEC route): no header row for the plumbing, real header + concepts retained, children promoted to the scaffold's depth rather than over-indented.
• Verified against the real AAPL FY2023 holon through the store route: 0 scaffold header rows remain in the income statement; members/totals reflow one level up under the section header.
• Full test:all (format, lint, typecheck, 75 tests, build) passes.