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/tables.dart

@@ -8,6 +8,10 @@ class MoodEntries extends Table {
   IntColumn get moodLevel => integer()(); // 1–5
   TextColumn get note => text().nullable()();
   DateTimeColumn get createdAt => dateTime().withDefault(currentDateAndTime)();
+  IntColumn get sleepMinutes => integer().nullable()();
+  IntColumn get energyLevel => integer().nullable()();
+  IntColumn get positivityLevel => integer().nullable()();
+  IntColumn get selfWorthLevel => integer().nullable()();
 }
 
 // ─── Activities ──────────────────────────────────────────────────────────────