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>

routes/exercises.py

@@ -0,0 +1,113 @@
+from flask import Blueprint, render_template, redirect, url_for, flash, request
+from models import db, Assessment, Exercise, GradingElement
+from forms import ExerciseForm, GradingElementForm
+
+bp = Blueprint('exercises', __name__)
+
+# Exercise routes
+@bp.route('/assessments/<int:assessment_id>/exercises/new', methods=['GET', 'POST'])
+def new(assessment_id):
+    assessment = Assessment.query.get_or_404(assessment_id)
+    form = ExerciseForm()
+    
+    # Set default order to next available
+    if form.order.data == 1:  # Only if it's the default value
+        max_order = db.session.query(db.func.max(Exercise.order)).filter_by(assessment_id=assessment_id).scalar()
+        form.order.data = (max_order or 0) + 1
+    
+    if form.validate_on_submit():
+        exercise = Exercise(
+            assessment_id=assessment_id,
+            title=form.title.data,
+            description=form.description.data,
+            order=form.order.data
+        )
+        db.session.add(exercise)
+        db.session.commit()
+        flash('Exercice créé avec succès !', 'success')
+        return redirect(url_for('exercises.detail', assessment_id=assessment_id, id=exercise.id))
+    
+    return render_template('exercise_form.html', form=form, assessment=assessment, title='Nouvel exercice')
+
+@bp.route('/assessments/<int:assessment_id>/exercises/<int:id>')
+def detail(assessment_id, id):
+    assessment = Assessment.query.get_or_404(assessment_id)
+    exercise = Exercise.query.filter_by(id=id, assessment_id=assessment_id).first_or_404()
+    return render_template('exercise_detail.html', assessment=assessment, exercise=exercise)
+
+@bp.route('/assessments/<int:assessment_id>/exercises/<int:id>/edit', methods=['GET', 'POST'])
+def edit(assessment_id, id):
+    assessment = Assessment.query.get_or_404(assessment_id)
+    exercise = Exercise.query.filter_by(id=id, assessment_id=assessment_id).first_or_404()
+    form = ExerciseForm(obj=exercise)
+    
+    if form.validate_on_submit():
+        exercise.title = form.title.data
+        exercise.description = form.description.data
+        exercise.order = form.order.data
+        db.session.commit()
+        flash('Exercice modifié avec succès !', 'success')
+        return redirect(url_for('exercises.detail', assessment_id=assessment_id, id=exercise.id))
+    
+    return render_template('exercise_form.html', form=form, assessment=assessment, exercise=exercise, title='Modifier l\'exercice')
+
+@bp.route('/assessments/<int:assessment_id>/exercises/<int:id>/delete', methods=['POST'])
+def delete(assessment_id, id):
+    assessment = Assessment.query.get_or_404(assessment_id)
+    exercise = Exercise.query.filter_by(id=id, assessment_id=assessment_id).first_or_404()
+    db.session.delete(exercise)
+    db.session.commit()
+    flash('Exercice supprimé avec succès !', 'success')
+    return redirect(url_for('assessments.detail', id=assessment_id))
+
+# GradingElement routes
+@bp.route('/assessments/<int:assessment_id>/exercises/<int:exercise_id>/elements/new', methods=['GET', 'POST'])
+def new_grading_element(assessment_id, exercise_id):
+    assessment = Assessment.query.get_or_404(assessment_id)
+    exercise = Exercise.query.filter_by(id=exercise_id, assessment_id=assessment_id).first_or_404()
+    form = GradingElementForm()
+    
+    if form.validate_on_submit():
+        element = GradingElement(
+            exercise_id=exercise_id,
+            label=form.label.data,
+            description=form.description.data,
+            skill=form.skill.data,
+            max_points=form.max_points.data,
+            grading_type=form.grading_type.data
+        )
+        db.session.add(element)
+        db.session.commit()
+        flash('Élément de notation créé avec succès !', 'success')
+        return redirect(url_for('exercises.detail', assessment_id=assessment_id, id=exercise_id))
+    
+    return render_template('grading_element_form.html', form=form, assessment=assessment, exercise=exercise, title='Nouvel élément de notation')
+
+@bp.route('/assessments/<int:assessment_id>/exercises/<int:exercise_id>/elements/<int:id>/edit', methods=['GET', 'POST'])
+def edit_grading_element(assessment_id, exercise_id, id):
+    assessment = Assessment.query.get_or_404(assessment_id)
+    exercise = Exercise.query.filter_by(id=exercise_id, assessment_id=assessment_id).first_or_404()
+    element = GradingElement.query.filter_by(id=id, exercise_id=exercise_id).first_or_404()
+    form = GradingElementForm(obj=element)
+    
+    if form.validate_on_submit():
+        element.label = form.label.data
+        element.description = form.description.data
+        element.skill = form.skill.data
+        element.max_points = form.max_points.data
+        element.grading_type = form.grading_type.data
+        db.session.commit()
+        flash('Élément de notation modifié avec succès !', 'success')
+        return redirect(url_for('exercises.detail', assessment_id=assessment_id, id=exercise_id))
+    
+    return render_template('grading_element_form.html', form=form, assessment=assessment, exercise=exercise, element=element, title='Modifier l\'élément de notation')
+
+@bp.route('/assessments/<int:assessment_id>/exercises/<int:exercise_id>/elements/<int:id>/delete', methods=['POST'])
+def delete_grading_element(assessment_id, exercise_id, id):
+    assessment = Assessment.query.get_or_404(assessment_id)
+    exercise = Exercise.query.filter_by(id=exercise_id, assessment_id=assessment_id).first_or_404()
+    element = GradingElement.query.filter_by(id=id, exercise_id=exercise_id).first_or_404()
+    db.session.delete(element)
+    db.session.commit()
+    flash('Élément de notation supprimé avec succès !', 'success')
+    return redirect(url_for('exercises.detail', assessment_id=assessment_id, id=exercise_id))