Match Finder table behavior and improve performance

[lyc280705]

What changed

• lock the Name column before AppKit begins a header drag and prevent every table header from entering a selected state
• allow the remaining columns to reorder only to the right of Name
• keep the table document width synchronized with the visible columns so fitted tables cannot scroll horizontally
• retain Finder-style first-column window resizing and enable overflow only after the first column reaches its minimum width
• support the current 7-Zip -slt attribute format when previewing 7Z archives
• cache selected-item metadata, archive summaries, and filtered entries; avoid redundant full-table reloads, toolbar refreshes, and sub-percent progress updates
• use lighter native motion that respects Reduce Motion
• add AppKit and archive round-trip regression tests and run them in GitHub Actions
• bump release build to 2.6.32

Root cause

The previous delegate rejected the Name column only after AppKit had already entered its header-drag path, and other columns could still propose index 0. The table columns were visually fitted, but the NSTableView document frame retained a wider horizontal range. Unrelated SwiftUI state changes also called reloadData() and recomputed archive-derived data.

Validation

• work/CleanZipBuild/tests/run.sh
• warnings-as-errors Swift typecheck targeting macOS 14
• universal local build for arm64 and x86_64
• real-window header click/drag and window-resize checks
• ordinary and split ZIP/7Z creation, metadata exclusion, archive test, preview, and extraction
• package expansion, version, architecture, signature, checksum, and metadata checks