halkyon_base: a Serverpod module for sign-in, accounts and instance basics

What every Halkyon server has, taken from Halkyon Learn's: anonymous,
GitHub and email-code sign-in with their endpoints, an account's ways
in and its deletion, the pruning of abandoned anonymous people, of
sign-up attempts and of expired codes, and the instance's basics (the
sign-in ways offered, the source link, the minimum app build, where
people's data and its backups are). Endpoints sit under the nickname
`base`. A host configures it in one place before its pod starts: its
name for the mails, its source link, its minimum build, and hooks that
delete its own data with a person.

The tables keep Learn's names, columns and indexes, so a host moving
onto the module migrates nothing but version rows. Server package under
the SSPL, client under the AGPL, as Learn's are.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

packages/halkyon_base_server/test/unit/data_location_test.dart

@@ -0,0 +1,44 @@
+import 'package:halkyon_base_server/base.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group("Where the operator says the instance's data is", () {
+    test("is a country's code or the European Union's", () {
+      expect(dataLocationFrom('CH'), 'CH');
+      expect(dataLocationFrom('EU'), 'EU');
+    });
+
+    test('is read in either case, around spaces', () {
+      expect(dataLocationFrom(' ch '), 'CH');
+    });
+
+    test('is nothing where it is unset, empty or no code', () {
+      expect(dataLocationFrom(null), isNull);
+      expect(dataLocationFrom(''), isNull);
+      expect(dataLocationFrom('Switzerland'), isNull);
+      expect(dataLocationFrom('C1'), isNull);
+    });
+
+    test('is never "none": the data is somewhere', () {
+      expect(dataLocationFrom('none'), isNull);
+    });
+  });
+
+  group('Where the operator says its backups are', () {
+    test("is a country's code or the European Union's", () {
+      expect(backupLocationFrom('ch'), 'CH');
+      expect(backupLocationFrom('EU'), 'EU');
+    });
+
+    test('may be none, in either case', () {
+      expect(backupLocationFrom('none'), noBackups);
+      expect(backupLocationFrom('NONE'), noBackups);
+    });
+
+    test('is nothing where it is unset, empty or no code', () {
+      expect(backupLocationFrom(null), isNull);
+      expect(backupLocationFrom(''), isNull);
+      expect(backupLocationFrom('Hetzner'), isNull);
+    });
+  });
+}