Remove Add Transaction feature and clean all related code

Deleted files:
- AddTransactionView.swift
- TransactionRepository.swift
- Transaction+CoreDataClass.swift

Cleaned files:
- SourceDetailViewModel: removed transactions published property,
  showingAddTransaction flag, transactionRepository dependency,
  addTransaction() and deleteTransaction() methods
- SourceDetailView: removed transactionsSection, TransactionRow struct,
  Add Transaction button from quickActions, sheet presentation
- InvestmentSource+CoreDataClass: removed transactions NSManaged property,
  transactionsArray, totalInvested, totalDividends, totalFees computed
  properties, and all transaction Core Data accessors
- SettingsViewModel: removed "Transaction" from resetAllData entity list
- SampleDataService: removed transactionRepository and sample transaction

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

PortfolioJournal/ViewModels/SourceDetailViewModel.swift

@@ -11,14 +11,12 @@ class SourceDetailViewModel: ObservableObject {
     @Published var metrics: InvestmentMetrics = .empty
     @Published var predictions: [Prediction] = []
     @Published var predictionResult: PredictionResult?
-    @Published var transactions: [Transaction] = []
     @Published var isDeleted = false
 
     @Published var isLoading = false
     @Published var showingAddSnapshot = false
     @Published var showingEditSource = false
     @Published var showingPaywall = false
-    @Published var showingAddTransaction = false
     @Published var errorMessage: String?
 
     // MARK: - Chart Data
@@ -29,7 +27,6 @@ class SourceDetailViewModel: ObservableObject {
 
     private let snapshotRepository: SnapshotRepository
     private let sourceRepository: InvestmentSourceRepository
-    private let transactionRepository: TransactionRepository
     private let calculationService: CalculationService
     private let predictionEngine: PredictionEngine
     private let freemiumValidator: FreemiumValidator
@@ -46,7 +43,6 @@ class SourceDetailViewModel: ObservableObject {
         source: InvestmentSource,
         snapshotRepository: SnapshotRepository? = nil,
         sourceRepository: InvestmentSourceRepository? = nil,
-        transactionRepository: TransactionRepository? = nil,
         calculationService: CalculationService? = nil,
         predictionEngine: PredictionEngine? = nil,
         iapService: IAPService
@@ -55,7 +51,6 @@ class SourceDetailViewModel: ObservableObject {
         self.sourceName = source.name
         self.snapshotRepository = snapshotRepository ?? SnapshotRepository()
         self.sourceRepository = sourceRepository ?? InvestmentSourceRepository()
-        self.transactionRepository = transactionRepository ?? TransactionRepository()
         self.calculationService = calculationService ?? .shared
         self.predictionEngine = predictionEngine ?? .shared
         self.freemiumValidator = FreemiumValidator(iapService: iapService)
@@ -147,8 +142,6 @@ class SourceDetailViewModel: ObservableObject {
                     }
                 }
 
-                // Transactions update independently
-                self.transactions = transactionRepository.fetchTransactions(for: source)
             }
             self.isRefreshing = false
         }
@@ -191,33 +184,6 @@ class SourceDetailViewModel: ObservableObject {
         refreshData()
     }
 
-    // MARK: - Transaction Actions
-
-    func addTransaction(
-        type: TransactionType,
-        date: Date,
-        shares: Decimal?,
-        price: Decimal?,
-        amount: Decimal?,
-        notes: String?
-    ) {
-        transactionRepository.createTransaction(
-            source: source,
-            type: type,
-            date: date,
-            shares: shares,
-            price: price,
-            amount: amount,
-            notes: notes
-        )
-        refreshData()
-    }
-
-    func deleteTransaction(_ transaction: Transaction) {
-        transactionRepository.deleteTransaction(transaction)
-        refreshData()
-    }
-
     // MARK: - Source Actions
 
     func updateSource(