feat(import): bring the account's own mood vocabulary along

A full backup carries the account's own mood tags, rated factors and
tag groups, and the JSON import left them out: a mood entry imported
into another account landed without every link to a tag the person had
made.

Before the entries are written, every key they or the file name is
resolved once. A catalogue tag or one the account owns is used as it
is; an own tag whose label the file states differently is kept, never
overwritten, and named in keptMoodTagKeys (keptMoodCategoryKeys for a
group). A tag the file defines and the account lacks is created in its
group, the group created the same way, within the account's caps of 50
tags and 12 groups. A key another account of the server holds comes
over under a key derived from the account and the file's key, so a
second import of the same file finds the copy instead of minting
another. The links are written through that resolution, own rated
factors included, inside the entry's transaction; anything unresolved
is still dropped and named. The import card names kept keys in all
nine locales.

The field-coverage guard now holds the backup's customMoodTags and
customMoodTagCategories to the import schema. The round trip moves a
backup to another server (the same seeded catalogue, none of the
account's rows), imports it into a fresh account and compares the
re-export, own tags, group and rated factor included; a second case
imports into another account of the same server, and a third keeps a
renamed own tag.

docs/integrations/data-import.md

@@ -72,10 +72,17 @@ in the backup and `""` in the export, reads as absent, a backup's deletion
 records are skipped and counted, and a reading in a display unit (lb, °F,
 mmol/L) is converted to the stored one.
 
-A mood entry's tags and rated factors are linked by key. A key the
-importing account has no tag for, typically a tag another account made
-for itself, is dropped from that entry, and the response names it in
-`droppedTagKeys` or `droppedFactorKeys`. The rest of the entry lands.
+A mood entry's tags and rated factors are linked by key. A full backup
+also carries the account's own tags, rated factors and tag groups, and the
+import brings them along: a tag the importing account already has is used
+as it is, and one it lacks is created (within the account's limit of 50
+custom tags and 12 groups). The account's own tag is never overwritten: when
+the file names it differently, the account's name stays and the response
+lists the key in `keptMoodTagKeys` (`keptMoodCategoryKeys` for a group).
+Moving a file between two accounts of one server works too; the tags come
+over under keys of their own. A key the account cannot resolve at all is
+dropped from that entry and named in `droppedTagKeys` or
+`droppedFactorKeys`, and the rest of the entry lands.
 
 ### Measurement entry