feat(use-case-compiler): MC-based compliance questionnaires with scoring

Implements the Use-Case Compiler that turns Master Controls into
interactive compliance audits. 5 templates (Vendor Check, SAST/DAST,
DSGVO, NIS2, CRA), deterministic + LLM question generation, scoring
engine with regulation/severity breakdown, and gap detection.

- Backend: 9 API endpoints, 22 unit tests (all pass)
- Frontend: Template selector, questionnaire, result dashboard
- Migration 027: usecase_audits + usecase_answers tables

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

ai-compliance-sdk/migrations/027_usecase_audits.sql

@@ -0,0 +1,39 @@
+-- Use-Case Compiler: Audits + Answers
+-- Turns Master Controls into interactive questionnaires
+
+CREATE TABLE IF NOT EXISTS compliance.usecase_audits (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id UUID NOT NULL,
+    template_id VARCHAR(100) NOT NULL,
+    name VARCHAR(200) NOT NULL,
+    target_name VARCHAR(200),
+    status VARCHAR(20) DEFAULT 'draft',
+    total_questions INT DEFAULT 0,
+    answered_questions INT DEFAULT 0,
+    compliance_score FLOAT DEFAULT 0,
+    questions JSONB DEFAULT '[]',
+    created_at TIMESTAMPTZ DEFAULT NOW(),
+    updated_at TIMESTAMPTZ DEFAULT NOW(),
+    completed_at TIMESTAMPTZ
+);
+
+CREATE INDEX IF NOT EXISTS idx_usecase_audits_tenant
+    ON compliance.usecase_audits (tenant_id);
+CREATE INDEX IF NOT EXISTS idx_usecase_audits_template
+    ON compliance.usecase_audits (template_id);
+
+CREATE TABLE IF NOT EXISTS compliance.usecase_answers (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    audit_id UUID NOT NULL REFERENCES compliance.usecase_audits(id) ON DELETE CASCADE,
+    question_id VARCHAR(50) NOT NULL,
+    mc_id VARCHAR(50),
+    answer JSONB NOT NULL,
+    evidence_ids JSONB DEFAULT '[]',
+    status VARCHAR(20) DEFAULT 'answered',
+    answered_at TIMESTAMPTZ DEFAULT NOW()
+);
+
+CREATE INDEX IF NOT EXISTS idx_usecase_answers_audit
+    ON compliance.usecase_answers (audit_id);
+CREATE UNIQUE INDEX IF NOT EXISTS idx_usecase_answers_unique
+    ON compliance.usecase_answers (audit_id, question_id);