fix: Make migration 007 idempotent (IF NOT EXISTS + ON CONFLICT)

CRITICAL FIX: Migration 007 failed beim Startup wegen existierendem Index

Problem:
- Migration 007 wurde teilweise angewendet (Spalten + Indexes erstellt)
- Bei erneutem Versuch: 'idx_skills_category already exists' → Abbruch
- Tabellen (training_styles, training_characters, etc.) nicht erstellt
- Katalog-Endpoints → 500 Error (UndefinedTable)

Lösung:
- Alle CREATE TABLE → CREATE TABLE IF NOT EXISTS
- Alle CREATE INDEX → CREATE INDEX IF NOT EXISTS
- ALTER TABLE → DO $$ BEGIN IF NOT EXISTS ... END $$
- Alle INSERT → ON CONFLICT (name) DO NOTHING

Migration kann jetzt beliebig oft ausgeführt werden ohne Fehler.

backend/migrations/007_exercise_catalogs.sql

@@ -3,7 +3,7 @@
 -- Beschreibung: Dynamische Kataloge statt Hard-Coding
 
 -- Fokusbereiche (statt hard-coded)
-CREATE TABLE focus_areas (
+CREATE TABLE IF NOT EXISTS focus_areas (
     id SERIAL PRIMARY KEY,
     name VARCHAR(100) NOT NULL UNIQUE,
     abbreviation VARCHAR(20),
@@ -16,10 +16,10 @@ CREATE TABLE focus_areas (
     updated_at TIMESTAMP DEFAULT NOW()
 );
 
-CREATE INDEX idx_focus_areas_status ON focus_areas(status);
+CREATE INDEX IF NOT EXISTS idx_focus_areas_status ON focus_areas(status);
 
 -- Trainingsstile (NEU: Shotokan, Goju-Ryu, etc.)
-CREATE TABLE training_styles (
+CREATE TABLE IF NOT EXISTS training_styles (
     id SERIAL PRIMARY KEY,
     name VARCHAR(100) NOT NULL UNIQUE,
     abbreviation VARCHAR(20),
@@ -31,11 +31,11 @@ CREATE TABLE training_styles (
     updated_at TIMESTAMP DEFAULT NOW()
 );
 
-CREATE INDEX idx_training_styles_status ON training_styles(status);
+CREATE INDEX IF NOT EXISTS idx_training_styles_status ON training_styles(status);
-CREATE INDEX idx_training_styles_parent ON training_styles(parent_style_id);
+CREATE INDEX IF NOT EXISTS idx_training_styles_parent ON training_styles(parent_style_id);
 
 -- Trainingscharaktere (statt hard-coded)
-CREATE TABLE training_characters (
+CREATE TABLE IF NOT EXISTS training_characters (
     id SERIAL PRIMARY KEY,
     name VARCHAR(100) NOT NULL UNIQUE,
     description TEXT,
@@ -45,10 +45,10 @@ CREATE TABLE training_characters (
     updated_at TIMESTAMP DEFAULT NOW()
 );
 
-CREATE INDEX idx_training_characters_status ON training_characters(status);
+CREATE INDEX IF NOT EXISTS idx_training_characters_status ON training_characters(status);
 
 -- Fähigkeitsbereiche (Kategorien für Skills)
-CREATE TABLE skill_categories (
+CREATE TABLE IF NOT EXISTS skill_categories (
     id SERIAL PRIMARY KEY,
     name VARCHAR(100) NOT NULL UNIQUE,
     description TEXT,
@@ -59,35 +59,53 @@ CREATE TABLE skill_categories (
     updated_at TIMESTAMP DEFAULT NOW()
 );
 
-CREATE INDEX idx_skill_categories_status ON skill_categories(status);
+CREATE INDEX IF NOT EXISTS idx_skill_categories_status ON skill_categories(status);
-CREATE INDEX idx_skill_categories_parent ON skill_categories(parent_category_id);
+CREATE INDEX IF NOT EXISTS idx_skill_categories_parent ON skill_categories(parent_category_id);
 
 -- Skills erweitern (Verknüpfung mit Kategorien)
-ALTER TABLE skills
+DO $$
-ADD COLUMN category_id INT REFERENCES skill_categories(id),
+BEGIN
-ADD COLUMN parent_skill_id INT REFERENCES skills(id),  -- Hierarchie: Tsuki → Mae-Zuki
+    IF NOT EXISTS (SELECT 1 FROM information_schema.columns WHERE table_name='skills' AND column_name='category_id') THEN
-ADD COLUMN level INT CHECK (level BETWEEN 1 AND 10),  -- Schwierigkeitsgrad
+        ALTER TABLE skills ADD COLUMN category_id INT REFERENCES skill_categories(id);
-ADD COLUMN sort_order INT;
+    END IF;
+    IF NOT EXISTS (SELECT 1 FROM information_schema.columns WHERE table_name='skills' AND column_name='parent_skill_id') THEN
+        ALTER TABLE skills ADD COLUMN parent_skill_id INT REFERENCES skills(id);
+    END IF;
+    IF NOT EXISTS (SELECT 1 FROM information_schema.columns WHERE table_name='skills' AND column_name='level') THEN
+        ALTER TABLE skills ADD COLUMN level INT CHECK (level BETWEEN 1 AND 10);
+    END IF;
+    IF NOT EXISTS (SELECT 1 FROM information_schema.columns WHERE table_name='skills' AND column_name='sort_order') THEN
+        ALTER TABLE skills ADD COLUMN sort_order INT;
+    END IF;
+END $$;
 
-CREATE INDEX idx_skills_category ON skills(category_id);
+CREATE INDEX IF NOT EXISTS idx_skills_category ON skills(category_id);
-CREATE INDEX idx_skills_parent ON skills(parent_skill_id);
+CREATE INDEX IF NOT EXISTS idx_skills_parent ON skills(parent_skill_id);
 
 -- Exercises erweitern
-ALTER TABLE exercises
+DO $$
-ADD COLUMN training_style_id INT REFERENCES training_styles(id),
+BEGIN
-ADD COLUMN training_character_id INT REFERENCES training_characters(id),
+    IF NOT EXISTS (SELECT 1 FROM information_schema.columns WHERE table_name='exercises' AND column_name='training_style_id') THEN
-ADD COLUMN focus_area_id INT REFERENCES focus_areas(id);
+        ALTER TABLE exercises ADD COLUMN training_style_id INT REFERENCES training_styles(id);
+    END IF;
+    IF NOT EXISTS (SELECT 1 FROM information_schema.columns WHERE table_name='exercises' AND column_name='training_character_id') THEN
+        ALTER TABLE exercises ADD COLUMN training_character_id INT REFERENCES training_characters(id);
+    END IF;
+    IF NOT EXISTS (SELECT 1 FROM information_schema.columns WHERE table_name='exercises' AND column_name='focus_area_id') THEN
+        ALTER TABLE exercises ADD COLUMN focus_area_id INT REFERENCES focus_areas(id);
+    END IF;
+END $$;
 
 -- Alte text-basierte Spalten können später deprecated werden
 -- ALTER TABLE exercises DROP COLUMN focus_area;  -- später, nach Migration
 -- ALTER TABLE exercises DROP COLUMN training_character;  -- später, nach Migration
 
-CREATE INDEX idx_exercises_style ON exercises(training_style_id);
+CREATE INDEX IF NOT EXISTS idx_exercises_style ON exercises(training_style_id);
-CREATE INDEX idx_exercises_character ON exercises(training_character_id);
+CREATE INDEX IF NOT EXISTS idx_exercises_character ON exercises(training_character_id);
-CREATE INDEX idx_exercises_focus_area ON exercises(focus_area_id);
+CREATE INDEX IF NOT EXISTS idx_exercises_focus_area ON exercises(focus_area_id);
 
 -- Trainer-Fokusbereich-Zuordnung (Welcher Trainer arbeitet in welchen Fokusbereichen?)
-CREATE TABLE trainer_focus_areas (
+CREATE TABLE IF NOT EXISTS trainer_focus_areas (
     id SERIAL PRIMARY KEY,
     profile_id INT REFERENCES profiles(id) ON DELETE CASCADE,
     focus_area_id INT REFERENCES focus_areas(id) ON DELETE CASCADE,
@@ -96,21 +114,23 @@ CREATE TABLE trainer_focus_areas (
     UNIQUE(profile_id, focus_area_id)
 );
 
-CREATE INDEX idx_trainer_focus_areas_profile ON trainer_focus_areas(profile_id);
+CREATE INDEX IF NOT EXISTS idx_trainer_focus_areas_profile ON trainer_focus_areas(profile_id);
-CREATE INDEX idx_trainer_focus_areas_focus ON trainer_focus_areas(focus_area_id);
+CREATE INDEX IF NOT EXISTS idx_trainer_focus_areas_focus ON trainer_focus_areas(focus_area_id);
 
 -- Basis-Daten einfügen
 INSERT INTO focus_areas (name, abbreviation, description, color, icon, sort_order) VALUES
 ('Karate', 'KAR', 'Traditionelles Karate', '#1D9E75', '🥋', 1),
 ('Selbstverteidigung', 'SV', 'Praktische Selbstverteidigung', '#D85A30', '🛡️', 2),
-('Gewaltschutz', 'GS', 'Gewaltprävention und Deeskalation', '#EF9F27', '🤝', 3);
+('Gewaltschutz', 'GS', 'Gewaltprävention und Deeskalation', '#EF9F27', '🤝', 3)
+ON CONFLICT (name) DO NOTHING;
 
 INSERT INTO training_styles (name, abbreviation, description, sort_order) VALUES
 ('Shotokan', 'SHO', 'Shotokan-Karate', 1),
 ('Goju-Ryu', 'GJR', 'Goju-Ryu-Karate', 2),
 ('Wado-Ryu', 'WAD', 'Wado-Ryu-Karate', 3),
 ('Shito-Ryu', 'SHI', 'Shito-Ryu-Karate', 4),
-('Kyokushin', 'KYO', 'Kyokushin-Karate', 5);
+('Kyokushin', 'KYO', 'Kyokushin-Karate', 5)
+ON CONFLICT (name) DO NOTHING;
 
 INSERT INTO training_characters (name, description, sort_order) VALUES
 ('Grundlage', 'Einführung und Basisvermittlung', 1),
@@ -118,7 +138,8 @@ INSERT INTO training_characters (name, description, sort_order) VALUES
 ('Vertiefung', 'Vertiefung und Spezialisierung', 3),
 ('Festigung', 'Wiederholung und Festigung', 4),
 ('Diagnose', 'Leistungsdiagnose und Test', 5),
-('Wettkampf', 'Wettkampfvorbereitung', 6);
+('Wettkampf', 'Wettkampfvorbereitung', 6)
+ON CONFLICT (name) DO NOTHING;
 
 INSERT INTO skill_categories (name, description, sort_order) VALUES
 ('Kihon', 'Grundschultechniken', 1),
@@ -126,4 +147,5 @@ INSERT INTO skill_categories (name, description, sort_order) VALUES
 ('Kata', 'Formen', 3),
 ('Selbstverteidigung', 'SV-Techniken', 4),
 ('Fitness', 'Kondition und Athletik', 5),
-('Mental', 'Mentale Fähigkeiten', 6);
+('Mental', 'Mentale Fähigkeiten', 6)
+ON CONFLICT (name) DO NOTHING;