refactor: remove unreachable code paths and unused members

Drops dead code across services, models, utils and widgets, including the
connection auth service, which had no implementer, and the Live TV DVR
provisioning models, which had no caller.

Tests that only covered deleted behaviour are removed or trimmed. No
behaviour change.

lib/database/app_database.dart

@@ -950,6 +950,7 @@ class AppDatabase extends _$AppDatabase {
   }
 
   /// Get pending watch actions for a specific server
+  @visibleForTesting
   Future<List<OfflineWatchProgressItem>> getPendingWatchActionsForServer(ServerId serverId, {String? profileId}) {
     return (select(offlineWatchProgress)
           ..where(
@@ -979,6 +980,7 @@ class AppDatabase extends _$AppDatabase {
   }
 
   /// Get the latest action for a specific item
+  @visibleForTesting
   Future<OfflineWatchProgressItem?> getLatestWatchAction(
     String globalKey, {
     String? profileId,

lib/database/download_operations.dart

@@ -1,6 +1,7 @@
 import 'dart:convert';
 
 import 'package:drift/drift.dart';
+import 'package:flutter/foundation.dart';
 import '../media/ids.dart';
 
 import 'app_database.dart';
@@ -138,6 +139,7 @@ extension DownloadDatabaseOperations on AppDatabase {
     return (await _validDownloadOwnerRows(globalKey)).length;
   }
 
+  @visibleForTesting
   Future<bool> hasDownloadOwner(String globalKey, {String? excludingProfileId}) async {
     final rows = await _validDownloadOwnerRows(globalKey, excludingProfileId: excludingProfileId);
     return rows.isNotEmpty;
@@ -573,6 +575,7 @@ extension DownloadDatabaseOperations on AppDatabase {
     return (await query.map((row) => row.read(count) ?? 0).getSingle());
   }
 
+  @visibleForTesting
   Future<Set<String>> getReferencedDownloadSafRoots() async {
     final rows =
         await (selectOnly(downloadedMedia)