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/assessments.py

@@ -0,0 +1,55 @@
+from flask import Blueprint, render_template, redirect, url_for, flash, request
+from models import db, Assessment, ClassGroup
+from forms import AssessmentForm
+
+bp = Blueprint('assessments', __name__, url_prefix='/assessments')
+
+@bp.route('/')
+def list():
+    assessments = Assessment.query.join(ClassGroup).order_by(Assessment.date.desc()).all()
+    return render_template('assessments.html', assessments=assessments)
+
+@bp.route('/new', methods=['GET', 'POST'])
+def new():
+    form = AssessmentForm()
+    if form.validate_on_submit():
+        assessment = Assessment(
+            title=form.title.data,
+            description=form.description.data,
+            date=form.date.data,
+            class_group_id=form.class_group_id.data,
+            coefficient=form.coefficient.data
+        )
+        db.session.add(assessment)
+        db.session.commit()
+        flash('Évaluation créée avec succès !', 'success')
+        return redirect(url_for('assessments.detail', id=assessment.id))
+    return render_template('assessment_form.html', form=form, title='Nouvelle évaluation')
+
+@bp.route('/<int:id>')
+def detail(id):
+    assessment = Assessment.query.get_or_404(id)
+    return render_template('assessment_detail.html', assessment=assessment)
+
+@bp.route('/<int:id>/edit', methods=['GET', 'POST'])
+def edit(id):
+    assessment = Assessment.query.get_or_404(id)
+    form = AssessmentForm(obj=assessment)
+    if form.validate_on_submit():
+        assessment.title = form.title.data
+        assessment.description = form.description.data
+        assessment.date = form.date.data
+        assessment.class_group_id = form.class_group_id.data
+        assessment.coefficient = form.coefficient.data
+        db.session.commit()
+        flash('Évaluation modifiée avec succès !', 'success')
+        return redirect(url_for('assessments.detail', id=assessment.id))
+    return render_template('assessment_form.html', form=form, title='Modifier l\'évaluation', assessment=assessment)
+
+@bp.route('/<int:id>/delete', methods=['POST'])
+def delete(id):
+    assessment = Assessment.query.get_or_404(id)
+    db.session.delete(assessment)
+    db.session.commit()
+    flash('Évaluation supprimée avec succès !', 'success')
+    return redirect(url_for('assessments.list'))