Add premium features roadmap and quick-win implementation guides

- PREMIUM_FEATURES_ROADMAP.md: Strategic feature roadmap for 3x-5x revenue expansion
  * Top 5 features: Board Autopilot, Insurance Integration, Predictive Modeling, Workflow Integration, Executive Monitoring
  * Revenue projections: $250K → $665K ARR over 3 years
  * 18+ feature ideas ranked by revenue, complexity, stickiness

- QUICK_WIN_FEATURES.md: Implementation guides for immediate value
  * Board Presentation Autopilot: 14-day implementation, $30K-$40K/year
  * Insurance Savings Calculator: 10-day implementation, $25K-$50K/year
  * Step-by-step code examples and deployment plan

Enables:
- 2.5x-3x wallet expansion per customer
- Shift from audit services to sticky SaaS
- 140-150% NRR with premium features
- $3.5M+ Year 1 revenue with premium offerings

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

frontend/src/lib/api.ts

@@ -56,6 +56,19 @@ export const api = {
 
   aiExplain: (findingId: string, question: string) =>
     request<{ question: string; answer: string }>(`/api/v1/ai/explain/${findingId}?question=${encodeURIComponent(question)}`),
+
+  aiExplainFinding: (findingId: string) =>
+    request<{
+      finding_id: string;
+      summary?: string;
+      business_impact?: string;
+      impact_level?: string;
+      remediation_steps?: string;
+      fix_priority?: string;
+      generated_at?: string;
+      status: "available" | "processing";
+      message?: string;
+    }>(`/api/v1/findings/${findingId}/ai-explain`),
 };
 
 // ─── Types ────────────────────────────────────────────────────────────────────