refactor: restructure codebase into modular architecture

- Split monolithic app.py (400+ lines) into organized modules
- Extract models, forms, and commands into separate files
- Implement Flask blueprints for route organization
- Maintain full functionality with cleaner architecture
- Update all templates to use new blueprint URLs
- Enhance README with technical documentation

Structure:
├── app.py (50 lines) - Flask app factory
├── models.py (62 lines) - SQLAlchemy models
├── forms.py (43 lines) - WTForms definitions
├── commands.py (74 lines) - CLI commands
└── routes/ - Blueprint modules for each feature

🤖 Generated with [Claude Code](https://claude.ai/code)

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

forms.py

@@ -0,0 +1,50 @@
+from flask_wtf import FlaskForm
+from wtforms import StringField, TextAreaField, FloatField, SelectField, DateField, IntegerField, SubmitField
+from wtforms.validators import DataRequired, Email, NumberRange, Optional, Length
+from datetime import date
+from models import ClassGroup
+
+class AssessmentForm(FlaskForm):
+    title = StringField('Titre', validators=[DataRequired(), Length(max=200)])
+    description = TextAreaField('Description', validators=[Optional()])
+    date = DateField('Date', validators=[DataRequired()], default=date.today)
+    class_group_id = SelectField('Classe', validators=[DataRequired()], coerce=int)
+    coefficient = FloatField('Coefficient', validators=[DataRequired(), NumberRange(min=0.1, max=10)], default=1.0)
+    submit = SubmitField('Enregistrer')
+    
+    def __init__(self, *args, **kwargs):
+        super(AssessmentForm, self).__init__(*args, **kwargs)
+        self.class_group_id.choices = [(cg.id, cg.name) for cg in ClassGroup.query.order_by(ClassGroup.name).all()]
+
+class ClassGroupForm(FlaskForm):
+    name = StringField('Nom de la classe', validators=[DataRequired(), Length(max=100)])
+    description = TextAreaField('Description', validators=[Optional()])
+    year = StringField('Année scolaire', validators=[DataRequired(), Length(max=20)], default="2024-2025")
+    submit = SubmitField('Enregistrer')
+
+class StudentForm(FlaskForm):
+    first_name = StringField('Prénom', validators=[DataRequired(), Length(max=100)])
+    last_name = StringField('Nom', validators=[DataRequired(), Length(max=100)])
+    email = StringField('Email', validators=[Optional(), Email(), Length(max=120)])
+    class_group_id = SelectField('Classe', validators=[DataRequired()], coerce=int)
+    submit = SubmitField('Enregistrer')
+    
+    def __init__(self, *args, **kwargs):
+        super(StudentForm, self).__init__(*args, **kwargs)
+        self.class_group_id.choices = [(cg.id, cg.name) for cg in ClassGroup.query.order_by(ClassGroup.name).all()]
+
+class ExerciseForm(FlaskForm):
+    title = StringField('Titre', validators=[DataRequired(), Length(max=200)])
+    description = TextAreaField('Description', validators=[Optional()])
+    order = IntegerField('Ordre', validators=[DataRequired(), NumberRange(min=1)], default=1)
+    submit = SubmitField('Enregistrer')
+
+class GradingElementForm(FlaskForm):
+    label = StringField('Libellé', validators=[DataRequired(), Length(max=200)])
+    description = TextAreaField('Description', validators=[Optional()])
+    skill = StringField('Compétence', validators=[Optional(), Length(max=200)])
+    max_points = FloatField('Barème (points max)', validators=[DataRequired(), NumberRange(min=0.1)], default=1.0)
+    grading_type = SelectField('Type de notation', validators=[DataRequired()], 
+                              choices=[('points', 'Points (ex: 2.5/4)'), ('score', 'Score (0, 1, 2, 3, .)')],
+                              default='points')
+    submit = SubmitField('Enregistrer')