feat: implement multi-step mood logging wizard

Adds sleep/energy/positivity/self-worth tracking columns to the database
(schema v2 migration), a new 5-option StepScale widget, per-answer chips
at the top of the screen, a 2×2 activity grid chip, and a full step-by-step
wizard flow: mood → sleep (first entry today only) → energy → positivity →
self-worth → activities → review+save.

lib/core/database/app_database.dart

@@ -32,7 +32,7 @@ class AppDatabase extends _$AppDatabase {
   AppDatabase() : super(_openConnection());
 
   @override
-  int get schemaVersion => 1;
+  int get schemaVersion => 2;
 
   @override
   MigrationStrategy get migration => MigrationStrategy(
@@ -41,7 +41,16 @@ class AppDatabase extends _$AppDatabase {
           await _seedDefaultActivities();
         },
         onUpgrade: (m, from, to) async {
-          // Future migrations go here
+          if (from < 2) {
+            await m.addColumn(moodEntries,
+                moodEntries.sleepMinutes as GeneratedColumn<Object>);
+            await m.addColumn(moodEntries,
+                moodEntries.energyLevel as GeneratedColumn<Object>);
+            await m.addColumn(moodEntries,
+                moodEntries.positivityLevel as GeneratedColumn<Object>);
+            await m.addColumn(moodEntries,
+                moodEntries.selfWorthLevel as GeneratedColumn<Object>);
+          }
         },
       );