fix(datagrid): copy only visible columns in their current order (#1354)

[datlechin]

Fixes #1354.

Problem

Copying rows from the data grid always emitted every column from the underlying result, ignoring which columns are hidden and the order the user arranged them in. The clipboard output didn't match what's on screen.

Fix

Add a small VisibleColumnProjection value type that maps a result's columns, column types, and cell values down to the visible set, in display order. indices == nil is the identity (all columns), and out-of-range indices are dropped (or treated as NULL for values), so it's safe against stale layouts.

TableViewCoordinator.visibleColumnDataIndices() returns the data indices of the currently visible columns (excludes hidden columns and the row-number column) in their on-screen order. Every copy path runs through the projection:

• TSV, with and without headers
• CSV, Markdown, JSON
• SQL INSERT / UPDATE
• single-cell drag/copy (TSV + HTML)

Tests

• VisibleColumnProjectionTests covers identity, reordering, hidden-column dropping, and out-of-range handling.
• RowOperationsManagerCopyTests gains cases for copying with a visible-column subset.

Notes

The diff also adds .analysis/ to .gitignore (local-only issue-analysis dir).