Milestone 2: module/model docs (MD, Sphinx RST, PDF) and work log

74 source modules documented with extracted signatures, JSDoc params,
imports, and call graphs. 10 first-class models (PriceRule through
StatusResponse) have their own MD/RST/PDF. Sphinx HTML builds from
docs/sphinx. Per-module PDFs in docs/modules-pdf and docs/models-pdf.

Middleware gates 2–6 and 10 pass on MOCK_VERAE without NATS.

Learned: RST includes are relative to the RST file; keep one PDF per
module; Add Numbers remains the only push required tomorrow.

docs/sphinx/models/TierConfig.md

@@ -0,0 +1,26 @@
+# TierConfig
+
+**Kind:** interface  
+**Defined in:** `packages/zappier/src/pricing.ts`
+
+## Fields
+
+| Field | Type | Meaning |
+|-------|------|---------|
+| `id` | `string` | free | pro | business or custom |
+| `name` | `string` | Display name |
+| `multiplier` | `number` | Applied once to list cents |
+| `monthlyCreditCents` | `number` | Included usage before Stripe/invoice |
+| `defaultRule` | `PriceRule?` | Price for unlisted operationIds |
+
+## Who constructs it
+
+PricingStore.getTiers()
+
+## Who consumes it
+
+`quoteCall`, `applyMonthlyCredit`, `admin tiers`, `portal`
+
+## Related modules
+
+See `docs/modules/` for the functions that take these types as parameters and the values they return.