feat(base)!: no anonymous accounts on the server (ADR 0020, D25)

The server's half of D25: every account has a way in, and the anonymous
accounts left from before go with the daily pruning.

- The module signs nobody in anonymously: `anonymousIdp` and
  `gitHubUpgrade` are gone, and so is linking GitHub at the register.
- A password is set only by someone whose address is theirs (a
  `firstPassword` code) or who signs in with GitHub alone (a fresh
  sign-in and a `signUp` code); an anonymous account is refused
  `wrongCredentials` before any code is used.
- SimpleLogin refuses to link onto a caller without `identified`
  (`wrongCaller`), the member's endpoint too, so nothing turns an
  anonymous account into one with a way in.
- `pruneAnonymousPeople` deletes every anonymous account left, however
  new, never one identified. Learn and Todo schedule it as
  `prune-accounts` and cancel the old `prune-abandoned-anonymous-people`
  entry once.
- Learn: someone without `identified` keeps no files;
  `FILE_LIMIT_ANONYMOUS_MB` is gone. `minimumAppBuild` is 23, as builds
  up to 22 start with an anonymous account.
- Learn's sync tests make their person and session by SQL in the
  development database, as Serverpod stores sessions.
- Docs, store listings and ADRs 0010, 0014, 0016, 0017 and 0019 amended.

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/integration/test_tools/serverpod_test_tools.dart

@@ -202,14 +202,10 @@ void withServerpod(
 class TestEndpoints {
   late final _AccountEndpoint account;
 
-  late final _AnonymousIdpEndpoint anonymousIdp;
-
   late final _EmailCodeEndpoint emailCode;
 
   late final _GitHubSignInEndpoint gitHubSignIn;
 
-  late final _GitHubUpgradeEndpoint gitHubUpgrade;
-
   late final _InstanceEndpoint instance;
 
   late final _KeysEndpoint keys;
@@ -240,10 +236,6 @@ class _InternalTestEndpoints extends TestEndpoints
       endpoints,
       serializationManager,
     );
-    anonymousIdp = _AnonymousIdpEndpoint(
-      endpoints,
-      serializationManager,
-    );
     emailCode = _EmailCodeEndpoint(
       endpoints,
       serializationManager,
@@ -252,10 +244,6 @@ class _InternalTestEndpoints extends TestEndpoints
       endpoints,
       serializationManager,
     );
-    gitHubUpgrade = _GitHubUpgradeEndpoint(
-      endpoints,
-      serializationManager,
-    );
     instance = _InstanceEndpoint(
       endpoints,
       serializationManager,
@@ -371,48 +359,6 @@ class _AccountEndpoint {
   }
 }
 
-class _AnonymousIdpEndpoint {
-  _AnonymousIdpEndpoint(
-    this._endpointDispatch,
-    this._serializationManager,
-  );
-
-  final _is.EndpointDispatch _endpointDispatch;
-
-  final _is.SerializationManager _serializationManager;
-
-  _ida.Future<_iacs.AuthSuccess> login(
-    _ist.TestSessionBuilder sessionBuilder, {
-    String? token,
-  }) async {
-    return _ist.callAwaitableFunctionAndHandleExceptions(() async {
-      var _localUniqueSession =
-          (sessionBuilder as _ist.InternalTestSessionBuilder).internalBuild(
-            endpoint: 'anonymousIdp',
-            method: 'login',
-          );
-      try {
-        var _localCallContext = await _endpointDispatch.getMethodCallContext(
-          createSessionCallback: (_) => _localUniqueSession,
-          endpointPath: 'anonymousIdp',
-          methodName: 'login',
-          parameters: _ist.testObjectToJson({'token': token}),
-          serializationManager: _serializationManager,
-        );
-        var _localReturnValue =
-            await (_localCallContext.method.call(
-                  _localUniqueSession,
-                  _localCallContext.arguments,
-                )
-                as _ida.Future<_iacs.AuthSuccess>);
-        return _localReturnValue;
-      } finally {
-        await _localUniqueSession.close();
-      }
-    });
-  }
-}
-
 class _EmailCodeEndpoint {
   _EmailCodeEndpoint(
     this._endpointDispatch,
@@ -509,54 +455,6 @@ class _GitHubSignInEndpoint {
   }
 }
 
-class _GitHubUpgradeEndpoint {
-  _GitHubUpgradeEndpoint(
-    this._endpointDispatch,
-    this._serializationManager,
-  );
-
-  final _is.EndpointDispatch _endpointDispatch;
-
-  final _is.SerializationManager _serializationManager;
-
-  _ida.Future<void> upgrade(
-    _ist.TestSessionBuilder sessionBuilder, {
-    required String code,
-    required String codeVerifier,
-    required String redirectUri,
-  }) async {
-    return _ist.callAwaitableFunctionAndHandleExceptions(() async {
-      var _localUniqueSession =
-          (sessionBuilder as _ist.InternalTestSessionBuilder).internalBuild(
-            endpoint: 'gitHubUpgrade',
-            method: 'upgrade',
-          );
-      try {
-        var _localCallContext = await _endpointDispatch.getMethodCallContext(
-          createSessionCallback: (_) => _localUniqueSession,
-          endpointPath: 'gitHubUpgrade',
-          methodName: 'upgrade',
-          parameters: _ist.testObjectToJson({
-            'code': code,
-            'codeVerifier': codeVerifier,
-            'redirectUri': redirectUri,
-          }),
-          serializationManager: _serializationManager,
-        );
-        var _localReturnValue =
-            await (_localCallContext.method.call(
-                  _localUniqueSession,
-                  _localCallContext.arguments,
-                )
-                as _ida.Future<void>);
-        return _localReturnValue;
-      } finally {
-        await _localUniqueSession.close();
-      }
-    });
-  }
-}
-
 class _InstanceEndpoint {
   _InstanceEndpoint(
     this._endpointDispatch,