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/v0.2.117.ts

@@ -0,0 +1,13 @@
+import { VersionInfo } from '@start9labs/start-sdk'
+
+export const v_0_2_117 = VersionInfo.of({
+  version: '0.2.117:0',
+  releaseNotes: {
+    en_US:
+      "Fix credits-purchased-by-Pro-tenant going to the wrong pool. The relayHeaders() helper used by /api/credits/buy and the credit poll/sweep paths was unconditionally sending the operator's install ID + license key, regardless of whether the buyer was a Pro/Max signed-in tenant with their own license. Result: a Pro tenant's BTCPay invoice got stashed with the operator's license_fingerprint, the relay's BTCPay webhook credited the operator's license-keyed pool, and the tenant's own balance never moved. Now relayHeaders() routes by per-request identity: signed-in user with a license → use THEIR install ID + license; anon / free / single-mode → fall back to operator identity (unchanged behavior for those cases). Threaded `req` through every relay caller in credits-purchase.js including the sweepUnappliedPurchases helper.",
+  },
+  migrations: {
+    up: async ({ effects }) => {},
+    down: async ({ effects }) => {},
+  },
+})