feat: replace age integer with date_of_birth across backend and client

Store date_of_birth (DATE) instead of a static age integer so that age
is always computed dynamically from the stored date of birth.

- Migration 011: adds date_of_birth, backfills from age, drops age
- AgeFromDOB helper computes current age from YYYY-MM-DD string
- User model, repository SQL, and service validation updated
- Flutter: User.age becomes a computed getter; profile edit screen
  uses a date picker bounded to [today-120y, today-10y]

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/lib/features/profile/profile_screen.dart

@@ -336,7 +336,7 @@ class _EditProfileSheetState extends ConsumerState<EditProfileSheet> {
   late final TextEditingController _nameCtrl;
   late final TextEditingController _heightCtrl;
   late final TextEditingController _weightCtrl;
-  late final TextEditingController _ageCtrl;
+  DateTime? _selectedDob;
   String? _gender;
   String? _goal;
   String? _activity;
@@ -351,7 +351,8 @@ class _EditProfileSheetState extends ConsumerState<EditProfileSheet> {
     _heightCtrl = TextEditingController(text: u.heightCm?.toString() ?? '');
     _weightCtrl = TextEditingController(
         text: u.weightKg != null ? _fmt(u.weightKg!) : '');
-    _ageCtrl = TextEditingController(text: u.age?.toString() ?? '');
+    _selectedDob =
+        u.dateOfBirth != null ? DateTime.tryParse(u.dateOfBirth!) : null;
     _gender = u.gender;
     _goal = u.goal;
     _activity = u.activity;
@@ -363,13 +364,24 @@ class _EditProfileSheetState extends ConsumerState<EditProfileSheet> {
     _nameCtrl.dispose();
     _heightCtrl.dispose();
     _weightCtrl.dispose();
-    _ageCtrl.dispose();
     super.dispose();
   }
 
   String _fmt(double w) =>
       w == w.truncateToDouble() ? w.toInt().toString() : w.toStringAsFixed(1);
 
+  Future<void> _pickDob() async {
+    final now = DateTime.now();
+    final initial = _selectedDob ?? DateTime(now.year - 25, now.month, now.day);
+    final picked = await showDatePicker(
+      context: context,
+      initialDate: initial,
+      firstDate: DateTime(now.year - 120),
+      lastDate: DateTime(now.year - 10, now.month, now.day),
+    );
+    if (picked != null) setState(() => _selectedDob = picked);
+  }
+
   Future<void> _save() async {
     if (!_formKey.currentState!.validate()) return;
     setState(() => _saving = true);
@@ -378,7 +390,11 @@ class _EditProfileSheetState extends ConsumerState<EditProfileSheet> {
       name: _nameCtrl.text.trim(),
       heightCm: int.tryParse(_heightCtrl.text),
       weightKg: double.tryParse(_weightCtrl.text),
-      age: int.tryParse(_ageCtrl.text),
+      dateOfBirth: _selectedDob != null
+          ? '${_selectedDob!.year.toString().padLeft(4, '0')}-'
+              '${_selectedDob!.month.toString().padLeft(2, '0')}-'
+              '${_selectedDob!.day.toString().padLeft(2, '0')}'
+          : null,
       gender: _gender,
       goal: _goal,
       activity: _activity,
@@ -506,21 +522,21 @@ class _EditProfileSheetState extends ConsumerState<EditProfileSheet> {
                     ),
                     const SizedBox(height: 12),
 
-                    // Age
-                    TextFormField(
-                      controller: _ageCtrl,
-                      decoration:
-                          const InputDecoration(labelText: 'Возраст (лет)'),
-                      keyboardType: TextInputType.number,
-                      inputFormatters: [
-                        FilteringTextInputFormatter.digitsOnly
-                      ],
-                      validator: (v) {
-                        if (v == null || v.isEmpty) return null;
-                        final n = int.tryParse(v);
-                        if (n == null || n < 10 || n > 120) return '10–120';
-                        return null;
-                      },
+                    // Date of birth
+                    InkWell(
+                      onTap: _pickDob,
+                      child: InputDecorator(
+                        decoration:
+                            const InputDecoration(labelText: 'Дата рождения'),
+                        child: Text(
+                          _selectedDob != null
+                              ? '${_selectedDob!.day.toString().padLeft(2, '0')}.'
+                                  '${_selectedDob!.month.toString().padLeft(2, '0')}.'
+                                  '${_selectedDob!.year}'
+                              : 'Не задано',
+                          style: Theme.of(context).textTheme.bodyMedium,
+                        ),
+                      ),
                     ),
                     const SizedBox(height: 20),
 

client/lib/features/profile/profile_service.dart

@@ -12,7 +12,7 @@ class UpdateProfileRequest {
   final String? name;
   final int? heightCm;
   final double? weightKg;
-  final int? age;
+  final String? dateOfBirth;
   final String? gender;
   final String? activity;
   final String? goal;
@@ -22,7 +22,7 @@ class UpdateProfileRequest {
     this.name,
     this.heightCm,
     this.weightKg,
-    this.age,
+    this.dateOfBirth,
     this.gender,
     this.activity,
     this.goal,
@@ -34,7 +34,7 @@ class UpdateProfileRequest {
     if (name != null) map['name'] = name;
     if (heightCm != null) map['height_cm'] = heightCm;
     if (weightKg != null) map['weight_kg'] = weightKg;
-    if (age != null) map['age'] = age;
+    if (dateOfBirth != null) map['date_of_birth'] = dateOfBirth;
     if (gender != null) map['gender'] = gender;
     if (activity != null) map['activity'] = activity;
     if (goal != null) map['goal'] = goal;