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/v0.2.105.ts

@@ -0,0 +1,13 @@
+import { VersionInfo } from '@start9labs/start-sdk'
+
+export const v_0_2_105 = VersionInfo.of({
+  version: '0.2.105:0',
+  releaseNotes: {
+    en_US:
+      "Two mobile polish items. (1) Silent retry on the magic-link send button. iOS Safari sometimes aborts the very first fetch from a cold tab with a generic 'Load failed' TypeError; the user previously had to manually click again. The Free signup path in the tier modal, the Pro/Max license-purchase path, and the standalone /auth.html magic-link form all now retry once silently with a ~500ms backoff. Server errors (4xx/5xx) are NOT retried — those are deliberate responses, not transport flakes. (2) Pro / Max upgrade entries in the mobile hamburger menu for signed-in free users. Previously the menu only exposed 'Buy more credits' which made plan upgrades a multi-tap drilldown through settings. Now signed-in users who aren't already on Pro or Max see 'Upgrade to Pro' and 'Upgrade to Max' below their credit line. Each entry opens the in-app license purchase modal with the relevant tier pre-selected, jumping straight to the discount-entry step.",
+  },
+  migrations: {
+    up: async ({ effects }) => {},
+    down: async ({ effects }) => {},
+  },
+})