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/v0.2.100.ts

@@ -0,0 +1,13 @@
+import { VersionInfo } from '@start9labs/start-sdk'
+
+export const v_0_2_100 = VersionInfo.of({
+  version: '0.2.100:0',
+  releaseNotes: {
+    en_US:
+      "Revert the anon-buyer recovery-email field added in v0.2.99. Asking an anon visitor for an email at the credit-purchase step defeats the value-prop of anon credit purchase. The mobile-menu Sign up entry (also added in v0.2.99) stays in place. The cross-cookie-jar edge case (e.g., Superhuman opening the magic link in DuckDuckGo while the credits were bought in Safari) is now a documented known limitation — sign up first if you want credits portable across browsers.",
+  },
+  migrations: {
+    up: async ({ effects }) => {},
+    down: async ({ effects }) => {},
+  },
+})