We need to redo this repo

ATM (after `gc --prune now`) we are already at

```
$> du -scm .git/objects
1673 .git/objects
1673 total
```

with the worktree containing only 224MB of text files. We need

- [ ] avoid producing a new version of the file if only some "non-consequential" fields changed (#25)
- [ ] check if we do get more reasonable diffs and possibly expand the list of fields to exclude from consideration
- [ ] move this repo aside (on github and locally) and start "a new one" with all prior extracts etc removed, and `git` repo reinitiated so we would get one with a more manageable .git/objects size

Start by reading issue #25 and reproducing the reported `du -scm .git/objects` measurement after `gc --prune now`. Determine which fields are non-consequential, verify whether excluding them produces smaller diffs, and define the cleanup and repository-reinitialization steps needed for a manageable Git history.

Written by the indexing model from the issue text.