Add removal dates to migration step comments (#559)

* Add removal dates to migration step comments

Document when each migration step reached main and when it can safely
be removed (one year after its first release).

* Fix step 3 removal date and improve comment wording

Step 3 was first released in v4.5.0 (2026-02-01), not v5.0.0.
Also use consistent "Released in" wording across all steps.

LoopFollow/ViewControllers/MainViewController.swift

@@ -145,22 +145,25 @@ class MainViewController: UIViewController, UITableViewDataSource, ChartViewDele
         // Capture before migrations run: true for existing users, false for fresh installs.
         let isExistingUser = Storage.shared.migrationStep.exists
 
+        // Step 1: Released in v3.0.0 (2025-07-07). Can be removed after 2026-07-07.
         if Storage.shared.migrationStep.value < 1 {
             Storage.shared.migrateStep1()
             Storage.shared.migrationStep.value = 1
         }
 
+        // Step 2: Released in v3.1.0 (2025-07-21). Can be removed after 2026-07-21.
         if Storage.shared.migrationStep.value < 2 {
             Storage.shared.migrateStep2()
             Storage.shared.migrationStep.value = 2
         }
 
+        // Step 3: Released in v4.5.0 (2026-02-01). Can be removed after 2027-02-01.
         if Storage.shared.migrationStep.value < 3 {
             Storage.shared.migrateStep3()
             Storage.shared.migrationStep.value = 3
         }
 
-        // TODO: This migration step can be deleted in March 2027. Check the commit for other places to cleanup.
+        // Step 4: Released in v5.0.0 (2026-03-20). Can be removed after 2027-03-20.
         if Storage.shared.migrationStep.value < 4 {
             // Existing users need to see the fat/protein order change banner.
             // New users never saw the old order, so mark it as already seen.
@@ -168,6 +171,7 @@ class MainViewController: UIViewController, UITableViewDataSource, ChartViewDele
             Storage.shared.migrationStep.value = 4
         }
 
+        // Step 5: Released in v5.0.0 (2026-03-20). Can be removed after 2027-03-20.
         if Storage.shared.migrationStep.value < 5 {
             Storage.shared.migrateStep5()
             Storage.shared.migrationStep.value = 5