fix(schedule): use start of day for date range queries

- Fix startDate to use Calendar.startOfDay instead of Date() to include
  games earlier in the current day
- Add SyncLogger for file-based sync logging viewable in Settings
- Add "View Sync Logs" button in Settings debug section
- Add diagnostics and NBA game logging to ScheduleViewModel
- Add dropped game logging to DataProvider.filterRichGames
- Use SyncLogger in SportsTimeApp and CloudKitService for sync operations

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

SportsTime/Core/Services/SyncLogger.swift

@@ -0,0 +1,79 @@
+//
+//  SyncLogger.swift
+//  SportsTime
+//
+//  File-based logger for sync operations.
+//  Writes to Documents/sync_log.txt for viewing in Settings.
+//
+
+import Foundation
+
+final class SyncLogger {
+    static let shared = SyncLogger()
+
+    private let fileURL: URL
+    private let maxLines = 500
+    private let queue = DispatchQueue(label: "com.sportstime.synclogger")
+
+    private init() {
+        let docs = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
+        fileURL = docs.appendingPathComponent("sync_log.txt")
+    }
+
+    // MARK: - Public API
+
+    func log(_ message: String) {
+        let timestamp = ISO8601DateFormatter().string(from: Date())
+        let line = "[\(timestamp)] \(message)\n"
+
+        // Also print to console
+        print(message)
+
+        queue.async { [weak self] in
+            self?.appendToFile(line)
+        }
+    }
+
+    func readLog() -> String {
+        guard FileManager.default.fileExists(atPath: fileURL.path) else {
+            return "No sync logs yet."
+        }
+        return (try? String(contentsOf: fileURL, encoding: .utf8)) ?? "Failed to read log."
+    }
+
+    func clearLog() {
+        queue.async { [weak self] in
+            guard let self = self else { return }
+            try? FileManager.default.removeItem(at: self.fileURL)
+        }
+    }
+
+    // MARK: - Private
+
+    private func appendToFile(_ line: String) {
+        if !FileManager.default.fileExists(atPath: fileURL.path) {
+            FileManager.default.createFile(atPath: fileURL.path, contents: nil)
+        }
+
+        guard let handle = try? FileHandle(forWritingTo: fileURL) else { return }
+        defer { try? handle.close() }
+
+        handle.seekToEndOfFile()
+        if let data = line.data(using: .utf8) {
+            handle.write(data)
+        }
+
+        // Trim if too large
+        trimIfNeeded()
+    }
+
+    private func trimIfNeeded() {
+        guard let content = try? String(contentsOf: fileURL, encoding: .utf8) else { return }
+        let lines = content.components(separatedBy: "\n")
+
+        if lines.count > maxLines {
+            let trimmed = lines.suffix(maxLines).joined(separator: "\n")
+            try? trimmed.write(to: fileURL, atomically: true, encoding: .utf8)
+        }
+    }
+}