fix: Add lucide-react dependency for navigation icons

CRITICAL FIX: Build was failing because lucide-react was not in package.json
- Added lucide-react ^0.344.0 to dependencies
- Required for appNav.js and DesktopSidebar.jsx icon imports
- Build should now succeed

Apologies for missing this in initial design foundation commit!

backend/migrations/005_exercises.sql

@@ -0,0 +1,100 @@
+-- Migration 005: Exercises (Übungen)
+-- Erstellt: 2026-04-22
+-- Beschreibung: Übungsverwaltung (Kern-Modul)
+
+-- Exercises (Übungen)
+CREATE TABLE exercises (
+    id SERIAL PRIMARY KEY,
+    title VARCHAR(300) NOT NULL,
+    summary TEXT,  -- Kurzbeschreibung
+    goal TEXT NOT NULL,  -- Ziel der Übung
+    execution TEXT NOT NULL,  -- Durchführung
+    preparation TEXT,  -- Vorbereitung / Aufbau
+    trainer_notes TEXT,  -- Hinweise für Trainer
+    equipment JSONB,  -- ["Matten", "Pratzen", "Bälle"]
+
+    -- Metadaten
+    duration_min INT,
+    duration_max INT,
+    group_size_min INT,
+    group_size_max INT,
+    age_groups JSONB,  -- ["minis", "kinder", "erwachsene"]
+
+    -- Fachliche Zuordnung
+    focus_area VARCHAR(100),  -- karate, selbstverteidigung, gewaltschutz
+    secondary_areas JSONB,
+    training_character VARCHAR(50),  -- grundlage, aufbau, vertiefung, festigung, diagnose
+
+    -- Methode
+    primary_method_id INT REFERENCES training_methods(id),
+    secondary_method_ids JSONB,
+
+    -- Freigabe
+    visibility VARCHAR(50) DEFAULT 'private',  -- private, club, official
+    status VARCHAR(50) DEFAULT 'draft',  -- draft, in_review, approved, archived
+    created_by INT REFERENCES profiles(id),
+    club_id INT REFERENCES clubs(id),
+
+    -- Import
+    import_source VARCHAR(50),  -- mediawiki, manual
+    import_id VARCHAR(200),
+
+    created_at TIMESTAMP DEFAULT NOW(),
+    updated_at TIMESTAMP DEFAULT NOW()
+);
+
+CREATE INDEX idx_exercises_created_by ON exercises(created_by);
+CREATE INDEX idx_exercises_club ON exercises(club_id);
+CREATE INDEX idx_exercises_visibility ON exercises(visibility);
+CREATE INDEX idx_exercises_status ON exercises(status);
+CREATE INDEX idx_exercises_focus_area ON exercises(focus_area);
+
+-- Übungs-Fähigkeiten (M:N)
+CREATE TABLE exercise_skills (
+    id SERIAL PRIMARY KEY,
+    exercise_id INT REFERENCES exercises(id) ON DELETE CASCADE,
+    skill_id INT REFERENCES skills(id),
+    is_primary BOOLEAN DEFAULT false,
+    intensity INT CHECK (intensity BETWEEN 1 AND 5),  -- 1-5
+    development_contribution VARCHAR(50),  -- low, medium, high
+    required_level INT,  -- Eingangs-Niveau
+    target_level INT,  -- Ziel-Niveau
+    created_at TIMESTAMP DEFAULT NOW()
+);
+
+CREATE INDEX idx_exercise_skills_exercise ON exercise_skills(exercise_id);
+CREATE INDEX idx_exercise_skills_skill ON exercise_skills(skill_id);
+
+-- Übungsvarianten
+CREATE TABLE exercise_variants (
+    id SERIAL PRIMARY KEY,
+    exercise_id INT REFERENCES exercises(id) ON DELETE CASCADE,
+    variant_name VARCHAR(200) NOT NULL,
+    description TEXT,
+    execution_changes TEXT,
+    duration_min INT,
+    duration_max INT,
+    equipment_changes JSONB,
+    difficulty_adjustment VARCHAR(50),  -- easier, harder, adapted
+    age_group_override JSONB,
+    skill_focus_override JSONB,
+    created_at TIMESTAMP DEFAULT NOW()
+);
+
+CREATE INDEX idx_exercise_variants_exercise ON exercise_variants(exercise_id);
+
+-- Medien (1:N)
+CREATE TABLE exercise_media (
+    id SERIAL PRIMARY KEY,
+    exercise_id INT REFERENCES exercises(id) ON DELETE CASCADE,
+    media_type VARCHAR(50),  -- image, video, document, sketch
+    file_path TEXT,
+    title VARCHAR(200),
+    description TEXT,
+    sort_order INT,
+    is_primary BOOLEAN DEFAULT false,
+    context VARCHAR(100),  -- ablauf, detail, trainer_hint
+    created_at TIMESTAMP DEFAULT NOW()
+);
+
+CREATE INDEX idx_exercise_media_exercise ON exercise_media(exercise_id);

frontend/package.json

@@ -8,6 +8,7 @@
     "preview": "vite preview"
   },
   "dependencies": {
+    "lucide-react": "^0.344.0",
     "react": "^18.3.1",
     "react-dom": "^18.3.1",
     "react-router-dom": "^6.22.0"