feat(subscription): rename permit→subscription + monthly pricing

The "permit/lejet" feature is really a subscription. Full rename of the
mutable master data, plus a recurring monthly price.

- DB (migration 0004, data-preserving ALTER RENAME): permits→subscriptions,
  permit_credentials/_plates→subscription_*, sessions.permit_id→subscription_id.
- Pricing: per-subscription priceMinor + period(monthly) + currency, with a
  site default (site_config.subscription_monthly_price_minor) pre-filling the form.
- Server: subscription-flow.ts (SubscriptionFlow), routes/subscriptions.ts
  (/api/subscriptions). Web: SubscriptionManager, route, i18n (sq Abonimet/en).
- The signed ledger `permitId` payload is intentionally kept — immutable
  hash-chained history; renaming it would break verification of past events.

Deferred (wiki notes): fee collection into the ledger/shift (a shift-attributed
payment), LPR/ANPR plate source, time-of-day access windows (overnight subscriber).

Also carries the device-footer UI surface (api DeviceStatus, router mount,
i18n devices) due to shared-file overlap with the preceding footer commit.

Verified end-to-end on a fresh DB and migration on a live-DB copy (sessions
preserved). Live DB migrated. Full monorepo builds clean.

Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V

apps/server/src/routes/site.ts

@@ -23,18 +23,23 @@ interface SiteConfigBody extends Partial<Record<TextField, string | null>> {
   capacity?: number | null;
   /** Default for the booth "print exit ticket" checkbox (booth-geography knob). */
   exitVoucherDefault?: boolean;
+  /** Site default monthly subscription price in minor units (pre-fills the form). */
+  subscriptionMonthlyPriceMinor?: number | null;
 }
 
-/** Shape returned by GET/PUT: capacity + the booth flag + every metadata field. */
-type SiteConfig = { capacity: number | null; exitVoucherDefault: boolean } & Record<
-  TextField,
-  string | null
->;
+/** Shape returned by GET/PUT: capacity + the booth flag + the subscription default
+ *  + every metadata field. */
+type SiteConfig = {
+  capacity: number | null;
+  exitVoucherDefault: boolean;
+  subscriptionMonthlyPriceMinor: number | null;
+} & Record<TextField, string | null>;
 
 function toSiteConfig(row: typeof siteConfig.$inferSelect | undefined): SiteConfig {
   const out = {
     capacity: row?.capacity ?? null,
     exitVoucherDefault: row?.exitVoucherDefault ?? false,
+    subscriptionMonthlyPriceMinor: row?.subscriptionMonthlyPriceMinor ?? null,
   } as SiteConfig;
   for (const f of TEXT_FIELDS) out[f] = row?.[f] ?? null;
   return out;
@@ -79,6 +84,13 @@ export async function siteRoutes(app: FastifyInstance, db: Db): Promise<void> {
       }
       patch.exitVoucherDefault = body.exitVoucherDefault;
     }
+    if ("subscriptionMonthlyPriceMinor" in body) {
+      const p = body.subscriptionMonthlyPriceMinor;
+      if (p != null && (!Number.isInteger(p) || p < 0)) {
+        return reply.code(400).send({ error: "subscriptionMonthlyPriceMinor must be a non-negative integer or null" });
+      }
+      patch.subscriptionMonthlyPriceMinor = p ?? null;
+    }
     for (const f of TEXT_FIELDS) {
       if (f in body) patch[f] = normText(body[f]);
     }