P2 slice 9: put the old copies aside after an adoption

`wanderbooks books put-aside ID DATA-DIR [--vault DIR --vault-key FILE]
[PATH...]` moves the old copies of adopted books (their data folder, their
TIN vault and its key, their settings file, the git history around them,
old exports) whole into numbered folders of their own in the root's
legacy/, a list of where each came from written and synced first. Nothing
is deleted. Refused unless the books hold everything the old copy does,
byte for byte (journal, stored files, vault records, key; what adoption
left behind and records the books sealed anew are listed and go aside
too); while a wanderbooks process holds it open for writing; when its
head moved since the preview; for links, paths named twice, inside the
root or missing, a vault or key given as a plain path, and paths on
another disk. Renames never replace anything, and a move cut short puts
back what it moved. Three review rounds of data safety.

The plan records the cutover's answers (Q-3: move the old copies aside;
the backup repository and folder).

Also: `connect`'s "the books fernhill' agent token" reads properly, and
the restart tests wait for a copied program to be runnable (a child forked
by another test while the copy was written made it "text file busy").

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T3gXMVt7XJPi6ens1or9Dj

plan/served.md

@@ -1334,7 +1334,9 @@ These are the only open owner questions. Ask them just before the move, one at a
 
 **Q-3. After the move, should the old copies of the books leave the project folder?** The project folder still holds the old journal and receipts (`books-data/`), the old sealed tax ID numbers (`vault/`), and the folder's git history, which contains the journal and receipts too. **Recommended: move them into the private folder's legacy area.** That is what "hidden away" means; otherwise an agent working in the project folder can still read the old copies. Nothing is deleted.
 
-**Crumbs to clear at the cutover** (owner, 2026-10-19: "migrate the first company books into the new scheme, data directory, clear out the crumbs"). After the adoption verifies, nothing of the old arrangement may be left where an agent or a later setup trips on it; every item is moved per Q-3 (into the root's `legacy/`, nothing deleted) or removed if it holds no books data:
+*Answered 2026-10-20 (the owner), one question at a time:* **Q-3: move them aside** (into the root's `legacy/`, nothing deleted). **Q-1's addresses:** the git remote is a new private repository on his server, `ssh://git@git.swaits.com:2222/swaits/fernhill-books-backup.git` (made private, with his go-ahead), and the folder is `~/Sync/wanderbooks-backups` (his Syncthing folder: a local disk, copied to his other devices; only this machine writes it).
+
+**Crumbs to clear at the cutover** (owner, 2026-10-19: "migrate the first company books into the new scheme, data directory, clear out the crumbs"). After the adoption verifies, nothing of the old arrangement may be left where an agent or a later setup trips on it; every item is moved per Q-3 (into the root's `legacy/`, nothing deleted, by `wanderbooks books put-aside ID DATA-DIR [PATH...]`, added at the cutover: only once the adopted books hold everything the old copy holds, only while nothing holds it open, only on the root's own disk, and a move cut short puts back what it moved) or removed if it holds no books data:
 - `books-data/` (journal, blobs, database, lock, `gui.log`) and `vault/`, and the project folder's git history holding them (Q-3);
 - the v1 vault key outside the books, `~/.config/wanderbooks/vault.key` (adoption copies it to the book's `keys/legacy.key`; the old one goes to `legacy/` with the vault);
 - `wanderbooks.toml` (its settings are in the books since P1; only `[viewer] open_at_start` remains, which the app's own preferences replace);