feat(base,app,keys): keys of shared spaces, sealed to each member

Step 3 of ADR 0044 (D3, D18, D19). A shared space's data keys are
sealed on a device to each member's public keys; the instance keeps
what devices sealed and never opens it.

- halkyon_keys: the safety code of two accounts' public keys
  (`safetyCode`), 60 digits, the same on both sides.
- halkyon_base: the register hands out accounts' public keys
  (`public-keys-of`, local and remote); the table `shared_space_key`
  and the endpoint `sharedSpaceKeys` (memberKeys, keysNeeded, seal,
  mine). Only the Owner and Editors seal, the first key sealed to a
  member stays, and a member's keys go with their membership. Every
  host's migration creates the table.
- halkyon_app: `ContentCipher` seals a key to another account and
  opens one sealed by another; `SharedKeys` shares a space's key with
  its members, seals keys to newcomers and opens the person's own,
  holding each member to the public keys `KeyPins` pinned on first
  sight (`key_pins.json` in the person's folder), a change refused
  until trusted anew.

Learn takes them into its `Privacy` in step 4.

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

@@ -83,10 +83,16 @@ import 'package:halkyon_base_server/src/generated/profile/profile_refusal.dart'
     as _idszjcpz;
 import 'package:halkyon_base_server/src/generated/shared_space/shared_space_info.dart'
     as _i582118y;
+import 'package:halkyon_base_server/src/generated/shared_space/shared_space_key_need.dart'
+    as _ije0apa9;
 import 'package:halkyon_base_server/src/generated/shared_space/shared_space_member_info.dart'
     as _izxzwa6x;
+import 'package:halkyon_base_server/src/generated/shared_space/shared_space_member_keys.dart'
+    as _ia0j1un6;
 import 'package:halkyon_base_server/src/generated/shared_space/shared_space_role.dart'
     as _i4jk9by9;
+import 'package:halkyon_base_server/src/generated/shared_space/shared_space_sealed_key.dart'
+    as _ik1elru1;
 import 'package:halkyon_base_server/src/generated/simplelogin/simplelogin_completed.dart'
     as _i8g1l2iv;
 import 'package:halkyon_base_server/src/generated/simplelogin/simplelogin_return.dart'
@@ -261,6 +267,8 @@ class TestEndpoints {
 
   late final _SharedSpaceEndpoint sharedSpace;
 
+  late final _SharedSpaceKeysEndpoint sharedSpaceKeys;
+
   late final _SimpleLoginEndpoint simpleLogin;
 }
 
@@ -335,6 +343,10 @@ class _InternalTestEndpoints extends TestEndpoints
       endpoints,
       serializationManager,
     );
+    sharedSpaceKeys = _SharedSpaceKeysEndpoint(
+      endpoints,
+      serializationManager,
+    );
     simpleLogin = _SimpleLoginEndpoint(
       endpoints,
       serializationManager,
@@ -3199,6 +3211,145 @@ class _SharedSpaceEndpoint {
   }
 }
 
+class _SharedSpaceKeysEndpoint {
+  _SharedSpaceKeysEndpoint(
+    this._endpointDispatch,
+    this._serializationManager,
+  );
+
+  final _is.EndpointDispatch _endpointDispatch;
+
+  final _is.SerializationManager _serializationManager;
+
+  _ida.Future<List<_ia0j1un6.SharedSpaceMemberKeys>> memberKeys(
+    _ist.TestSessionBuilder sessionBuilder,
+    _is.UuidValue space,
+  ) async {
+    return _ist.callAwaitableFunctionAndHandleExceptions(() async {
+      var _localUniqueSession =
+          (sessionBuilder as _ist.InternalTestSessionBuilder).internalBuild(
+            endpoint: 'sharedSpaceKeys',
+            method: 'memberKeys',
+          );
+      try {
+        var _localCallContext = await _endpointDispatch.getMethodCallContext(
+          createSessionCallback: (_) => _localUniqueSession,
+          endpointPath: 'sharedSpaceKeys',
+          methodName: 'memberKeys',
+          parameters: _ist.testObjectToJson({'space': space}),
+          serializationManager: _serializationManager,
+        );
+        var _localReturnValue =
+            await (_localCallContext.method.call(
+                  _localUniqueSession,
+                  _localCallContext.arguments,
+                )
+                as _ida.Future<List<_ia0j1un6.SharedSpaceMemberKeys>>);
+        return _localReturnValue;
+      } finally {
+        await _localUniqueSession.close();
+      }
+    });
+  }
+
+  _ida.Future<List<_ije0apa9.SharedSpaceKeyNeed>> keysNeeded(
+    _ist.TestSessionBuilder sessionBuilder,
+    _is.UuidValue space,
+  ) async {
+    return _ist.callAwaitableFunctionAndHandleExceptions(() async {
+      var _localUniqueSession =
+          (sessionBuilder as _ist.InternalTestSessionBuilder).internalBuild(
+            endpoint: 'sharedSpaceKeys',
+            method: 'keysNeeded',
+          );
+      try {
+        var _localCallContext = await _endpointDispatch.getMethodCallContext(
+          createSessionCallback: (_) => _localUniqueSession,
+          endpointPath: 'sharedSpaceKeys',
+          methodName: 'keysNeeded',
+          parameters: _ist.testObjectToJson({'space': space}),
+          serializationManager: _serializationManager,
+        );
+        var _localReturnValue =
+            await (_localCallContext.method.call(
+                  _localUniqueSession,
+                  _localCallContext.arguments,
+                )
+                as _ida.Future<List<_ije0apa9.SharedSpaceKeyNeed>>);
+        return _localReturnValue;
+      } finally {
+        await _localUniqueSession.close();
+      }
+    });
+  }
+
+  _ida.Future<void> seal(
+    _ist.TestSessionBuilder sessionBuilder,
+    _is.UuidValue space,
+    List<_ik1elru1.SharedSpaceSealedKey> keys,
+  ) async {
+    return _ist.callAwaitableFunctionAndHandleExceptions(() async {
+      var _localUniqueSession =
+          (sessionBuilder as _ist.InternalTestSessionBuilder).internalBuild(
+            endpoint: 'sharedSpaceKeys',
+            method: 'seal',
+          );
+      try {
+        var _localCallContext = await _endpointDispatch.getMethodCallContext(
+          createSessionCallback: (_) => _localUniqueSession,
+          endpointPath: 'sharedSpaceKeys',
+          methodName: 'seal',
+          parameters: _ist.testObjectToJson({
+            'space': space,
+            'keys': keys,
+          }),
+          serializationManager: _serializationManager,
+        );
+        var _localReturnValue =
+            await (_localCallContext.method.call(
+                  _localUniqueSession,
+                  _localCallContext.arguments,
+                )
+                as _ida.Future<void>);
+        return _localReturnValue;
+      } finally {
+        await _localUniqueSession.close();
+      }
+    });
+  }
+
+  _ida.Future<List<_ik1elru1.SharedSpaceSealedKey>> mine(
+    _ist.TestSessionBuilder sessionBuilder,
+    _is.UuidValue space,
+  ) async {
+    return _ist.callAwaitableFunctionAndHandleExceptions(() async {
+      var _localUniqueSession =
+          (sessionBuilder as _ist.InternalTestSessionBuilder).internalBuild(
+            endpoint: 'sharedSpaceKeys',
+            method: 'mine',
+          );
+      try {
+        var _localCallContext = await _endpointDispatch.getMethodCallContext(
+          createSessionCallback: (_) => _localUniqueSession,
+          endpointPath: 'sharedSpaceKeys',
+          methodName: 'mine',
+          parameters: _ist.testObjectToJson({'space': space}),
+          serializationManager: _serializationManager,
+        );
+        var _localReturnValue =
+            await (_localCallContext.method.call(
+                  _localUniqueSession,
+                  _localCallContext.arguments,
+                )
+                as _ida.Future<List<_ik1elru1.SharedSpaceSealedKey>>);
+        return _localReturnValue;
+      } finally {
+        await _localUniqueSession.close();
+      }
+    });
+  }
+}
+
 class _SimpleLoginEndpoint {
   _SimpleLoginEndpoint(
     this._endpointDispatch,