The previous .git directory was destroyed (only an empty .git/lfs stub
remained: no HEAD, refs, objects, or config), so prior commit history is
unrecoverable. This commit snapshots the current working tree as a fresh
baseline on `main`.

Provenance: this tree is a heavy restructure of harp-lab/Assemblage
(code moved under backend/, SQLModel + pydantic-v2 rewrite, Textual TUI,
Assemblage_dataset_cli submodule, 2025-2026 Alembic migrations). None of
the four upstream branches (master, linux_github, windows_github,
windows_vcpkg) share this layout, so upstream cannot reconstruct the lost
history; it is added as the `upstream` remote for reference only.

.gitignore hardened to exclude large data artifacts that would otherwise
break a commit: winpe.sqlite (102 GB), hf_binaries/ (361 GB),
data_refill/linux_licensed.duckdb (127 GB), and related
*.sqlite/*.duckdb/*.zst/*.xz/*.tar archives.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>