Add batch actions for multi-task completion (Phase 7)

Implement batch task completion feature allowing users to select and
complete multiple care tasks at once. Adds edit mode to Today View with
selection checkmarks, floating BatchActionBar, and confirmation dialog
for completing more than 3 tasks.

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

PlantGuideTests/CreateCareScheduleUseCaseTests.swift

@@ -157,7 +157,7 @@ final class CreateCareScheduleUseCaseTests: XCTestCase {
 
         // Then
         let wateringTasks = result.tasks.filter { $0.type == .watering }
-        XCTAssertTrue(wateringTasks.allSatisfy { $0.notes?.contains("thorough") ?? false })
+        XCTAssertTrue(wateringTasks.allSatisfy { $0.notes.contains("thorough") })
     }
 
     func testExecute_WateringTasks_HaveCorrectPlantID() async throws {
@@ -242,7 +242,7 @@ final class CreateCareScheduleUseCaseTests: XCTestCase {
 
         // Then
         let fertilizerTasks = result.tasks.filter { $0.type == .fertilizing }
-        XCTAssertTrue(fertilizerTasks.allSatisfy { $0.notes?.contains("highNitrogen") ?? false })
+        XCTAssertTrue(fertilizerTasks.allSatisfy { $0.notes.contains("highNitrogen") })
     }
 
     // MARK: - User Preferences Tests

PlantGuideTests/Mocks/MockCareScheduleRepository.swift

@@ -26,6 +26,7 @@ final class MockCareScheduleRepository: CareScheduleRepositoryProtocol, @uncheck
     var fetchAllTasksCallCount = 0
     var updateTaskCallCount = 0
     var deleteCallCount = 0
+    var batchCompleteCallCount = 0
 
     // MARK: - Error Configuration
 
@@ -35,6 +36,7 @@ final class MockCareScheduleRepository: CareScheduleRepositoryProtocol, @uncheck
     var shouldThrowOnFetchAllTasks = false
     var shouldThrowOnUpdateTask = false
     var shouldThrowOnDelete = false
+    var shouldThrowOnBatchComplete = false
 
     var errorToThrow: Error = NSError(
         domain: "MockError",
@@ -48,6 +50,7 @@ final class MockCareScheduleRepository: CareScheduleRepositoryProtocol, @uncheck
     var lastFetchedPlantID: UUID?
     var lastUpdatedTask: CareTask?
     var lastDeletedPlantID: UUID?
+    var lastBatchCompletedTaskIDs: Set<UUID>?
 
     // MARK: - CareScheduleRepositoryProtocol
 
@@ -111,6 +114,35 @@ final class MockCareScheduleRepository: CareScheduleRepositoryProtocol, @uncheck
         schedules.removeValue(forKey: plantID)
     }
 
+    func batchCompleteTasks(_ taskIDs: Set<UUID>) async throws {
+        batchCompleteCallCount += 1
+        lastBatchCompletedTaskIDs = taskIDs
+        if shouldThrowOnBatchComplete {
+            throw errorToThrow
+        }
+
+        let now = Date()
+        for (plantID, var schedule) in schedules {
+            var modified = false
+            for (index, task) in schedule.tasks.enumerated() {
+                if taskIDs.contains(task.id) && !task.isCompleted {
+                    schedule.tasks[index] = CareTask(
+                        id: task.id,
+                        plantID: task.plantID,
+                        type: task.type,
+                        scheduledDate: task.scheduledDate,
+                        completedDate: now,
+                        notes: task.notes
+                    )
+                    modified = true
+                }
+            }
+            if modified {
+                schedules[plantID] = schedule
+            }
+        }
+    }
+
     // MARK: - Helper Methods
 
     /// Resets all state for clean test setup
@@ -123,6 +155,7 @@ final class MockCareScheduleRepository: CareScheduleRepositoryProtocol, @uncheck
         fetchAllTasksCallCount = 0
         updateTaskCallCount = 0
         deleteCallCount = 0
+        batchCompleteCallCount = 0
 
         shouldThrowOnSave = false
         shouldThrowOnFetch = false
@@ -130,11 +163,13 @@ final class MockCareScheduleRepository: CareScheduleRepositoryProtocol, @uncheck
         shouldThrowOnFetchAllTasks = false
         shouldThrowOnUpdateTask = false
         shouldThrowOnDelete = false
+        shouldThrowOnBatchComplete = false
 
         lastSavedSchedule = nil
         lastFetchedPlantID = nil
         lastUpdatedTask = nil
         lastDeletedPlantID = nil
+        lastBatchCompletedTaskIDs = nil
     }
 
     /// Adds a schedule directly to storage (bypasses save method)