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/actions/setTrialCreditsPerVisitor.ts

@@ -0,0 +1,60 @@
+import { sdk } from '../sdk'
+import { configFile } from '../file-models/config.json'
+
+const { InputSpec, Value } = sdk
+
+// Anonymous-trial allowance per first-time visitor. Multi-tenant mode
+// only. When a visitor lands on the public Recaps URL without a session
+// cookie and submits a YouTube URL, the server issues them a
+// recap_anon_trial cookie with this many free summaries — no email,
+// no signup, no friction. After they're spent, the UI nudges them to
+// create an account for more credits.
+//
+// Trial summaries draw from the OPERATOR's relay credit pool, so this
+// number times the visitor volume sets the floor on your sample-cost
+// exposure. Tune downward if you see abuse, upward if you want a more
+// generous activation funnel. Set to 0 to disable trials entirely
+// (visitors immediately hit the sign-up gate).
+//
+// Defaults to 1 — enough to demo the value prop, tight enough that
+// scripted-signup abuse doesn't drain the pool fast.
+const inputSpec = InputSpec.of({
+  credits: Value.number({
+    name: 'Trial credits per anonymous visitor',
+    description:
+      'How many free summaries an unauthenticated visitor gets before being asked to sign up. Charged against your relay credit pool. Set to 0 to disable trials (immediate sign-up gate).',
+    required: true,
+    default: 1,
+    integer: true,
+    min: 0,
+    max: 5,
+  }),
+})
+
+export const setTrialCreditsPerVisitor = sdk.Action.withInput(
+  'set-trial-credits-per-visitor',
+
+  async ({ effects }) => ({
+    name: 'Set Trial Credits per Visitor',
+    description:
+      "How many free summaries anonymous visitors get on your multi-tenant Recaps before being prompted to sign up. Default: 1. Charged against your relay credit pool.",
+    warning: null,
+    allowedStatuses: 'any',
+    group: 'Multi-Tenant',
+    visibility: 'enabled',
+  }),
+
+  inputSpec,
+
+  async ({ effects }) => {
+    const config = await configFile.read().once()
+    return { credits: config?.trial_credits_per_visitor ?? 1 }
+  },
+
+  async ({ effects, input }) => {
+    await configFile.merge(effects, {
+      trial_credits_per_visitor: input.credits,
+    })
+    return null
+  },
+)