feat(chat): integrate chat project into monorepo with full app structure

- Restructure chat as apps/mobile, apps/web, apps/landing, backend
- Add NestJS backend for secure Azure OpenAI API calls
- Remove exposed API key from mobile app (security fix)
- Add shared chat-types package
- Create SvelteKit web app scaffold
- Create Astro landing page scaffold
- Update pnpm workspace configuration
- Add project-level CLAUDE.md documentation

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

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

chat/apps/mobile/scripts/create_usage_logs_table.sql

@@ -0,0 +1,122 @@
+-- Erstelle eine neue Tabelle für die Token-Nutzung und Kostenerfassung
+
+-- 1. Überprüfe, ob die usage_logs-Tabelle existiert
+DO $$
+BEGIN
+  IF NOT EXISTS (
+    SELECT FROM information_schema.tables 
+    WHERE table_schema = 'public' 
+    AND table_name = 'usage_logs'
+  ) THEN
+    -- Erstelle die usage_logs-Tabelle
+    CREATE TABLE public.usage_logs (
+      id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+      conversation_id UUID REFERENCES conversations(id) ON DELETE CASCADE,
+      message_id UUID REFERENCES messages(id) ON DELETE CASCADE,
+      user_id UUID REFERENCES auth.users(id),
+      model_id UUID REFERENCES models(id),
+      prompt_tokens INTEGER NOT NULL,
+      completion_tokens INTEGER NOT NULL,
+      total_tokens INTEGER NOT NULL,
+      estimated_cost DECIMAL(10, 6) NOT NULL,
+      created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
+    );
+    
+    RAISE NOTICE 'Tabelle usage_logs wurde erstellt.';
+  ELSE
+    RAISE NOTICE 'Tabelle usage_logs existiert bereits.';
+  END IF;
+END
+$$;
+
+-- 2. Aktiviere RLS für die usage_logs-Tabelle
+ALTER TABLE public.usage_logs ENABLE ROW LEVEL SECURITY;
+
+-- 3. Erstelle RLS-Richtlinien für usage_logs
+-- Benutzer können nur ihre eigenen Nutzungsdaten sehen
+DROP POLICY IF EXISTS usage_logs_select_policy ON usage_logs;
+CREATE POLICY usage_logs_select_policy
+ON usage_logs
+FOR SELECT
+TO authenticated
+USING (user_id = auth.uid());
+
+-- Nur über die Anwendung dürfen Einträge erstellt werden
+DROP POLICY IF EXISTS usage_logs_insert_policy ON usage_logs;
+CREATE POLICY usage_logs_insert_policy
+ON usage_logs
+FOR INSERT
+TO authenticated
+WITH CHECK (user_id = auth.uid());
+
+-- 4. Erweitere das Modell-Schema um Kosteninformationen
+DO $$
+BEGIN
+  IF NOT EXISTS (
+    SELECT FROM information_schema.columns 
+    WHERE table_schema = 'public' 
+    AND table_name = 'models' 
+    AND column_name = 'cost_settings'
+  ) THEN
+    ALTER TABLE public.models ADD COLUMN cost_settings JSONB DEFAULT '{"prompt_per_1k_tokens": 0.0001, "completion_per_1k_tokens": 0.0002}'::jsonb;
+    RAISE NOTICE 'Spalte cost_settings zur models-Tabelle hinzugefügt.';
+  ELSE
+    RAISE NOTICE 'Spalte cost_settings existiert bereits in der models-Tabelle.';
+  END IF;
+END
+$$;
+
+-- 5. Aktualisiere die vorhandenen Modelle mit Kosteninformationen
+UPDATE public.models
+SET cost_settings = jsonb_build_object(
+  'prompt_per_1k_tokens', CASE 
+    WHEN name LIKE '%GPT-O3-Mini%' THEN 0.0001
+    WHEN name LIKE '%GPT-4o-mini%' THEN 0.0001
+    WHEN name LIKE '%GPT-4o%' THEN 0.003
+    WHEN name LIKE '%GPT-4%' THEN 0.003
+    WHEN name LIKE '%GPT-3.5%' THEN 0.0001
+    WHEN name LIKE '%Claude%' THEN 0.0008
+    ELSE 0.0001
+  END,
+  'completion_per_1k_tokens', CASE 
+    WHEN name LIKE '%GPT-O3-Mini%' THEN 0.0002
+    WHEN name LIKE '%GPT-4o-mini%' THEN 0.0002
+    WHEN name LIKE '%GPT-4o%' THEN 0.006
+    WHEN name LIKE '%GPT-4%' THEN 0.006
+    WHEN name LIKE '%GPT-3.5%' THEN 0.0002
+    WHEN name LIKE '%Claude%' THEN 0.0024
+    ELSE 0.0002
+  END
+)
+WHERE cost_settings IS NULL OR cost_settings = '{}'::jsonb;
+
+-- 6. Funktion zur Berechnung der Kosten
+CREATE OR REPLACE FUNCTION calculate_token_cost(
+  p_prompt_tokens INTEGER,
+  p_completion_tokens INTEGER,
+  p_model_id UUID
+) RETURNS DECIMAL(10, 6) AS $$
+DECLARE
+  v_prompt_cost DECIMAL(10, 6);
+  v_completion_cost DECIMAL(10, 6);
+  v_cost_settings JSONB;
+  v_cost DECIMAL(10, 6);
+BEGIN
+  -- Hole die Kosteneinstellungen für das angegebene Modell
+  SELECT cost_settings INTO v_cost_settings
+  FROM models
+  WHERE id = p_model_id;
+  
+  -- Extrahiere die Kosten pro 1000 Token
+  v_prompt_cost := (v_cost_settings->>'prompt_per_1k_tokens')::DECIMAL;
+  v_completion_cost := (v_cost_settings->>'completion_per_1k_tokens')::DECIMAL;
+  
+  -- Berechne die Gesamtkosten
+  v_cost := (p_prompt_tokens * v_prompt_cost + p_completion_tokens * v_completion_cost) / 1000;
+  
+  RETURN ROUND(v_cost, 6);
+END;
+$$ LANGUAGE plpgsql;
+
+-- 7. Berechtigung zum Ausführen der Funktion
+GRANT EXECUTE ON FUNCTION calculate_token_cost TO authenticated;