feat(pitch-deck): add passwordless investor auth, audit logs, snapshots & PWA

Implement a complete investor access system for the pitch deck:

- Passwordless magic link auth (jose JWT + nodemailer SMTP)
- Per-investor audit logging (slide views, assumption changes, chat)
- Financial model snapshot persistence (auto-save/restore per investor)
- PWA support (manifest, service worker, offline caching, icons)
- Security safeguards (watermark overlay, rate limiting, anti-scraping
  headers, content protection, single-session enforcement)
- Admin API for invite/revoke/audit-log management
- Integrated into docker-compose.coolify.yml for production deployment

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

pitch-deck/lib/rate-limit.ts

@@ -0,0 +1,52 @@
+interface RateLimitEntry {
+  count: number
+  resetAt: number
+}
+
+const store = new Map<string, RateLimitEntry>()
+
+// Cleanup stale entries every 60 seconds
+setInterval(() => {
+  const now = Date.now()
+  for (const [key, entry] of store) {
+    if (entry.resetAt <= now) store.delete(key)
+  }
+}, 60_000)
+
+export interface RateLimitConfig {
+  /** Max requests in the window */
+  limit: number
+  /** Window size in seconds */
+  windowSec: number
+}
+
+export interface RateLimitResult {
+  allowed: boolean
+  remaining: number
+  resetAt: number
+}
+
+export function checkRateLimit(key: string, config: RateLimitConfig): RateLimitResult {
+  const now = Date.now()
+  const entry = store.get(key)
+
+  if (!entry || entry.resetAt <= now) {
+    store.set(key, { count: 1, resetAt: now + config.windowSec * 1000 })
+    return { allowed: true, remaining: config.limit - 1, resetAt: now + config.windowSec * 1000 }
+  }
+
+  if (entry.count >= config.limit) {
+    return { allowed: false, remaining: 0, resetAt: entry.resetAt }
+  }
+
+  entry.count++
+  return { allowed: true, remaining: config.limit - entry.count, resetAt: entry.resetAt }
+}
+
+// Preset configurations
+export const RATE_LIMITS = {
+  magicLink: { limit: 3, windowSec: 3600 } as RateLimitConfig,        // 3 per email per hour
+  authVerify: { limit: 10, windowSec: 900 } as RateLimitConfig,       // 10 per IP per 15min
+  api: { limit: 60, windowSec: 60 } as RateLimitConfig,               // 60 per session per minute
+  chat: { limit: 20, windowSec: 60 } as RateLimitConfig,              // 20 per session per minute
+} as const