Add multi-tenant cloud mode: self-serve purchase, credit metering, core-decoupling

Introduces RECAP_MODE=multi alongside single-mode self-host:
- Tenant auth + accounts (magic-link via System SMTP), per-tenant credit pool,
  anonymous trial minting with per-IP/-64 caps
- Self-serve Pro/Max purchase: inline Lightning (BTCPay) + card (Zaprite),
  prepaid 30-day periods, expiry-reminder emails
- Core-decoupling: relay owns cloud tier/expiry keyed by Recaps user-id
- SQLite (better-sqlite3) schema for multi-mode; filesystem unchanged for single
- StartOS actions/versions through 0.2.155

startos/versions/v0.2.97.ts

@@ -0,0 +1,12 @@
+import { VersionInfo } from '@start9labs/start-sdk'
+
+export const v_0_2_97 = VersionInfo.of({
+  version: '0.2.97:0',
+  releaseNotes: {
+    en_US: 'First-visit welcome modal. Brand-new anon visitors on a multi-tenant Recap (no recap_welcome_seen cookie) now see a one-time welcome card explaining what Recap is before they have to figure out the URL input from scratch. Six bullets: paste any link, AI topic summaries with timestamps, full transcript on demand, library + subscriptions, pay-your-way (anon / Bitcoin / Pro subscription / self-host with BYO keys), and the value-prop summary. Single "Get started" CTA dismisses with a 1-year cookie so the same browser never sees it again. Single-mode installs and signed-in users never see this — it\'s strictly the first-impression intro for fresh cloud visitors.',
+  },
+  migrations: {
+    up: async ({ effects }) => {},
+    down: async ({ effects }) => {},
+  },
+})