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/v0.2.139.ts

@@ -0,0 +1,13 @@
+import { VersionInfo } from '@start9labs/start-sdk'
+
+export const v_0_2_139 = VersionInfo.of({
+  version: '0.2.139:0',
+  releaseNotes: {
+    en_US:
+      "Audio-first \"Listen\" player polish: the play button now shows a pause icon while audio is playing (and vice-versa); swipe left/right on the card to move between topic summaries; a speed button cycles 1×–2× playback for both the summaries and the deep-dive source audio. Also made clip generation resilient — if a topic's audio stalls or fails, playback now skips ahead to the next ready topic instead of getting stuck, and a per-clip request timeout keeps one slow synth from blocking the rest.",
+  },
+  migrations: {
+    up: async ({ effects }) => {},
+    down: async ({ effects }) => {},
+  },
+})