feat: EU AI Database Registration (Art. 49) — Backend + Frontend

Backend (Go):
- DB Migration 023: ai_system_registrations Tabelle
- RegistrationStore: CRUD + Status-Management + Export-JSON
- RegistrationHandlers: 7 Endpoints (Create, List, Get, Update, Status, Prefill, Export)
- Routes in main.go: /sdk/v1/ai-registration/*

Frontend (Next.js):
- 6-Step Wizard: Anbieter → System → Klassifikation → Konformitaet → Trainingsdaten → Pruefung
- System-Karten mit Status-Badges (Entwurf/Bereit/Eingereicht/Registriert)
- JSON-Export fuer EU-Datenbank-Submission
- Status-Workflow: draft → ready → submitted → registered
- API Proxy Routes

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ai-compliance-sdk/migrations/023_ai_registration_schema.sql

@@ -0,0 +1,65 @@
+-- Migration 023: AI System Registration Schema (Art. 49 AI Act)
+-- Tracks EU AI Database registrations for High-Risk AI systems
+
+CREATE TABLE IF NOT EXISTS ai_system_registrations (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id UUID NOT NULL,
+
+    -- System identification
+    system_name VARCHAR(500) NOT NULL,
+    system_version VARCHAR(100),
+    system_description TEXT,
+    intended_purpose TEXT,
+
+    -- Provider info
+    provider_name VARCHAR(500),
+    provider_legal_form VARCHAR(200),
+    provider_address TEXT,
+    provider_country VARCHAR(10),
+    eu_representative_name VARCHAR(500),
+    eu_representative_contact TEXT,
+
+    -- Classification
+    risk_classification VARCHAR(50) DEFAULT 'not_classified',
+    -- CHECK (risk_classification IN ('not_classified', 'minimal_risk', 'limited_risk', 'high_risk', 'unacceptable'))
+    annex_iii_category VARCHAR(200),
+    gpai_classification VARCHAR(50) DEFAULT 'none',
+    -- CHECK (gpai_classification IN ('none', 'standard', 'systemic'))
+
+    -- Conformity
+    conformity_assessment_type VARCHAR(50),
+    -- CHECK (conformity_assessment_type IN ('internal', 'third_party', 'not_required'))
+    notified_body_name VARCHAR(500),
+    notified_body_id VARCHAR(100),
+    ce_marking BOOLEAN DEFAULT false,
+
+    -- Training data
+    training_data_categories JSONB DEFAULT '[]'::jsonb,
+    training_data_summary TEXT,
+
+    -- Registration status
+    registration_status VARCHAR(50) DEFAULT 'draft',
+    -- CHECK (registration_status IN ('draft', 'ready', 'submitted', 'registered', 'update_required', 'withdrawn'))
+    eu_database_id VARCHAR(200),
+    registration_date TIMESTAMPTZ,
+    last_update_date TIMESTAMPTZ,
+
+    -- Links to other assessments
+    ucca_assessment_id UUID,
+    decision_tree_result_id UUID,
+
+    -- Export data (cached JSON for EU submission)
+    export_data JSONB,
+
+    -- Audit
+    created_at TIMESTAMPTZ DEFAULT NOW(),
+    updated_at TIMESTAMPTZ DEFAULT NOW(),
+    created_by VARCHAR(200),
+    submitted_by VARCHAR(200)
+);
+
+-- Indexes
+CREATE INDEX IF NOT EXISTS idx_air_tenant ON ai_system_registrations (tenant_id);
+CREATE INDEX IF NOT EXISTS idx_air_status ON ai_system_registrations (registration_status);
+CREATE INDEX IF NOT EXISTS idx_air_classification ON ai_system_registrations (risk_classification);
+CREATE INDEX IF NOT EXISTS idx_air_ucca ON ai_system_registrations (ucca_assessment_id);