feat(auth): Learn's and Todo's servers take password sign-in

Their migrations add halkyon_base's five tables for passwords,
authenticators, recovery codes, resets and sign-ins begun (nothing
else), and their pruning forgets sign-ins never finished and
authenticators never confirmed, hourly, and every GitHub ID once
GitHub sign-in has ended, daily.

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

apps/learn/halkyon_learn_client/lib/migrations/migration_registry.dart

@@ -18,6 +18,7 @@ part '20261012162411835-studyset-deleted-at/migration.dart';
 part '20261019121406578-halkyon-base/migration.dart';
 part '20261019201023295-profiles-in-halkyon-base/migration.dart';
 part '20261019204112282-deletion-notices/migration.dart';
+part '20261020111943300-passwords/migration.dart';
 
 /// Migration registry for the client-side database.
 class MigrationRegistry {
@@ -38,6 +39,7 @@ class MigrationRegistry {
     _Migration20261019121406578_halkyon_base(),
     _Migration20261019201023295_profiles_in_halkyon_base(),
     _Migration20261019204112282_deletion_notices(),
+    _Migration20261020111943300_passwords(),
   ];
 
   /// List of all client-side database migration versions.