Implement Phase 6: automated bank sync (Plaid + SimpleFIN) & settings

Add automated transaction syncing via Plaid and SimpleFIN providers,
a Settings page for managing connections and account mappings,
background scheduled syncing, and sync history logging.

New backend: BankSync plugin project with PlaidSyncProvider and
SimpleFinSyncProvider, SyncConnection/LinkedAccount/SyncLog models,
AES-256 encryption service, BankSyncService orchestration,
BankSyncBackgroundService (15-min tick), and BankSyncController
(13 endpoints). EF migration creates sync_connections,
linked_accounts, and sync_logs tables.

New frontend: Settings view with 3 tabs (Profile, Bank Connections,
Sync History), bankSync API service, BankSyncComplete SignalR
notifications, and Settings nav item in sidebar + avatar dropdown.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/Purrse.Core/DTOs/BankSyncDtos.cs

@@ -0,0 +1,82 @@
+using Purrse.Core.Enums;
+
+namespace Purrse.Core.DTOs;
+
+// Plaid
+public record CreatePlaidConnectionRequest(string PublicToken);
+public record CreateLinkTokenResponse(string LinkToken, string Expiration);
+
+// SimpleFIN
+public record CreateSimpleFinConnectionRequest(string SetupToken);
+
+// Connection management
+public record SyncConnectionResponse(
+    Guid Id,
+    SyncProvider Provider,
+    string InstitutionName,
+    string? InstitutionId,
+    bool IsActive,
+    int SyncIntervalMinutes,
+    DateTime? LastSyncAt,
+    string? LastSyncError,
+    DateTime CreatedAt,
+    List<LinkedAccountResponse> LinkedAccounts);
+
+public record LinkedAccountResponse(
+    Guid Id,
+    string ExternalAccountId,
+    string ExternalAccountName,
+    string? ExternalAccountType,
+    string? ExternalAccountMask,
+    decimal? LastKnownBalance,
+    bool IsEnabled,
+    Guid? AccountId,
+    string? AccountName,
+    DateTime? LastSyncAt);
+
+public record UpdateConnectionRequest(bool IsActive, int SyncIntervalMinutes);
+
+// Account linking
+public record LinkAccountRequest(Guid LinkedAccountId, Guid? AccountId, bool AutoCreate);
+public record UpdateLinkedAccountRequest(Guid? AccountId, bool IsEnabled);
+
+public record DiscoveredAccountResponse(
+    string ExternalAccountId,
+    string Name,
+    string? Type,
+    string? Mask,
+    decimal? Balance,
+    string? Currency);
+
+// Sync results
+public record SyncResultResponse(
+    int TotalAccounts,
+    int AccountsSynced,
+    int TransactionsFetched,
+    int TransactionsImported,
+    int TransactionsSkipped,
+    List<SyncAccountResult> AccountResults);
+
+public record SyncAccountResult(
+    string ExternalAccountName,
+    string? PurrseAccountName,
+    int Fetched,
+    int Imported,
+    int Skipped,
+    string? Error);
+
+// Sync logs
+public record SyncLogResponse(
+    Guid Id,
+    Guid ConnectionId,
+    string InstitutionName,
+    Guid? LinkedAccountId,
+    string? LinkedAccountName,
+    SyncStatus Status,
+    int TransactionsFetched,
+    int TransactionsImported,
+    int TransactionsSkipped,
+    string? ErrorMessage,
+    DateTime StartedAt,
+    DateTime? CompletedAt,
+    TimeSpan? Duration);

src/Purrse.Core/Enums/SyncProvider.cs

@@ -0,0 +1,7 @@
+namespace Purrse.Core.Enums;
+
+public enum SyncProvider
+{
+    Plaid,
+    SimpleFIN
+}

src/Purrse.Core/Enums/SyncStatus.cs

@@ -0,0 +1,9 @@
+namespace Purrse.Core.Enums;
+
+public enum SyncStatus
+{
+    Success,
+    PartialSuccess,
+    Failed,
+    Running
+}

src/Purrse.Core/Interfaces/Services/IBankSyncService.cs

@@ -0,0 +1,31 @@
+using Purrse.Core.DTOs;
+
+namespace Purrse.Core.Interfaces.Services;
+
+public interface IBankSyncService
+{
+    // Connection CRUD
+    Task<List<SyncConnectionResponse>> GetConnectionsAsync(Guid userId);
+    Task<SyncConnectionResponse> GetConnectionAsync(Guid userId, Guid connectionId);
+    Task<SyncConnectionResponse> UpdateConnectionAsync(Guid userId, Guid connectionId, UpdateConnectionRequest request);
+    Task DeleteConnectionAsync(Guid userId, Guid connectionId);
+
+    // Plaid flow
+    Task<CreateLinkTokenResponse> CreatePlaidLinkTokenAsync(Guid userId);
+    Task<SyncConnectionResponse> CompletePlaidLinkAsync(Guid userId, CreatePlaidConnectionRequest request);
+
+    // SimpleFIN flow
+    Task<SyncConnectionResponse> CreateSimpleFinConnectionAsync(Guid userId, CreateSimpleFinConnectionRequest request);
+
+    // Account linking
+    Task<List<DiscoveredAccountResponse>> DiscoverAccountsAsync(Guid userId, Guid connectionId);
+    Task<LinkedAccountResponse> LinkAccountAsync(Guid userId, Guid connectionId, LinkAccountRequest request);
+    Task<LinkedAccountResponse> UpdateLinkedAccountAsync(Guid userId, Guid linkedAccountId, UpdateLinkedAccountRequest request);
+
+    // Sync
+    Task<SyncResultResponse> SyncNowAsync(Guid userId, Guid connectionId);
+    Task<SyncResultResponse> SyncAllAsync(Guid userId);
+
+    // Logs
+    Task<List<SyncLogResponse>> GetSyncLogsAsync(Guid userId, Guid? connectionId = null, int limit = 50);
+}

src/Purrse.Core/Interfaces/Services/IEncryptionService.cs

@@ -0,0 +1,7 @@
+namespace Purrse.Core.Interfaces.Services;
+
+public interface IEncryptionService
+{
+    string Encrypt(string plainText);
+    string Decrypt(string cipherText);
+}

src/Purrse.Core/Models/Account.cs

@@ -25,4 +25,5 @@ public class Account
     public ICollection<Transaction> Transactions { get; set; } = new List<Transaction>();
     public ICollection<InvestmentHolding> InvestmentHoldings { get; set; } = new List<InvestmentHolding>();
     public ICollection<Reconciliation> Reconciliations { get; set; } = new List<Reconciliation>();
+    public ICollection<LinkedAccount> LinkedAccounts { get; set; } = new List<LinkedAccount>();
 }

src/Purrse.Core/Models/LinkedAccount.cs

@@ -0,0 +1,19 @@
+namespace Purrse.Core.Models;
+
+public class LinkedAccount
+{
+    public Guid Id { get; set; }
+    public Guid SyncConnectionId { get; set; }
+    public Guid? AccountId { get; set; }
+    public string ExternalAccountId { get; set; } = string.Empty;
+    public string ExternalAccountName { get; set; } = string.Empty;
+    public string? ExternalAccountType { get; set; }
+    public string? ExternalAccountMask { get; set; }
+    public decimal? LastKnownBalance { get; set; }
+    public bool IsEnabled { get; set; } = true;
+    public DateTime? LastSyncAt { get; set; }
+    public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+
+    public SyncConnection SyncConnection { get; set; } = null!;
+    public Account? Account { get; set; }
+}

src/Purrse.Core/Models/SyncConnection.cs

@@ -0,0 +1,24 @@
+using Purrse.Core.Enums;
+
+namespace Purrse.Core.Models;
+
+public class SyncConnection
+{
+    public Guid Id { get; set; }
+    public Guid UserId { get; set; }
+    public SyncProvider Provider { get; set; }
+    public string InstitutionName { get; set; } = string.Empty;
+    public string? InstitutionId { get; set; }
+    public string EncryptedAccessToken { get; set; } = string.Empty;
+    public string? PlaidItemId { get; set; }
+    public bool IsActive { get; set; } = true;
+    public int SyncIntervalMinutes { get; set; } = 360;
+    public DateTime? LastSyncAt { get; set; }
+    public string? LastSyncError { get; set; }
+    public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+    public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
+
+    public User User { get; set; } = null!;
+    public ICollection<LinkedAccount> LinkedAccounts { get; set; } = new List<LinkedAccount>();
+    public ICollection<SyncLog> SyncLogs { get; set; } = new List<SyncLog>();
+}

src/Purrse.Core/Models/SyncLog.cs

@@ -0,0 +1,21 @@
+using Purrse.Core.Enums;
+
+namespace Purrse.Core.Models;
+
+public class SyncLog
+{
+    public Guid Id { get; set; }
+    public Guid SyncConnectionId { get; set; }
+    public Guid? LinkedAccountId { get; set; }
+    public SyncStatus Status { get; set; }
+    public int TransactionsFetched { get; set; }
+    public int TransactionsImported { get; set; }
+    public int TransactionsSkipped { get; set; }
+    public string? ErrorMessage { get; set; }
+    public DateTime StartedAt { get; set; }
+    public DateTime? CompletedAt { get; set; }
+    public TimeSpan? Duration { get; set; }
+
+    public SyncConnection SyncConnection { get; set; } = null!;
+    public LinkedAccount? LinkedAccount { get; set; }
+}

src/Purrse.Core/Models/User.cs

@@ -12,4 +12,5 @@ public class User
     public DateTime? RefreshTokenExpiresAt { get; set; }
 
     public ICollection<Account> Accounts { get; set; } = new List<Account>();
+    public ICollection<SyncConnection> SyncConnections { get; set; } = new List<SyncConnection>();
 }