Wire zappier-edge into the live stack and add billing department APIs

Fleet now spawns the real zappier and middleware processes. Metered
timestamp/receipt/hash calls proxy to middleware when ZAPPIER_UPSTREAM
is set. CS credits, sales per-customer pricing, and QuickBooks export
are separate repos plugged into zappier-edge admin.

scripts/gen-module-docs.py

@@ -40,6 +40,9 @@ REPO_READMES = [
     "zapier-user-docs",
     "docs-master",
     "verae-nats-process",
+    "zappier-customer-service",
+    "zappier-sales-pricing",
+    "zappier-accounting-export",
 ]
 
 SKIP_PARTS = {"test", "tests", "node_modules", "dist"}