Task: Review Go backend for missing modules

Identity

Read-only completeness review of the merged Go backend against ADR-003 and the current Next.js implementation: HTTP route surface, deep modules, provider engines, account lifecycle, ops scripts, and deployment artifacts.

No application, database, test, or deployment file was changed.
Facts were verified against the checked-in route-surface contract, source inventories, and binary strings; no claims based on task-record prose alone.

Route surface: complete parity. The checked-in contract has 66 method/path entries; Next.js exports 64 route handlers plus the two static file roots (/uploads, /generated-results), and the Go route_surface.go registers all 66. Zero routes missing in Go, zero unexpected extras.
Deep modules: all ADR-003 modules exist in Go — identity (legacy zhinian_session HMAC/chunking, password lifecycle, authorization), administration (accounts, organizations, status/archive/delete, legacy subject), assets (local FS + OSS adapters, bounded remote import), jobs/providers/orchestration (embedded WorkerLoop, retries, artifacts, Seedance settlement, signed Webhooks), billing/usage (integer-fen quote/wallet/ledger/catalog, super-admin quota exemption), templates/prompt/settings/logging, postgres (fail-closed, verified-CA TLS, readiness, claim/wallet functions, grants including platform_account_migrations), localstore, httpapi/publicapi (OpenAPI output), health/ready.
Provider engines: image jimeng/evolink/bailian (wan2.7-image-pro) and video seedance/bailian are all wired in Go; the current Next capability surface is only image.generate and video.generate, so Go matches it exactly. inpaint/upscale are legacy asset-source labels, not active capabilities.

Programmatic diff of contracts/http/route-surface.v1.json (66 entries) against Next route exports (64) and Go route_surface.go (66): contract minus Go is empty; Go minus Next is only the two static file routes.
Grep audits: provider engines, OSS, webhook HMAC, captcha proxy, WorkerLoop packages, admin account lifecycle, super-admin quota exemption.
Binary string scan of backend/zhinian-api confirms bailian image/video endpoints, seedance settlement, and OSS requirements are compiled in.

Ops tooling gaps (small, cutover-relevant, not runtime modules):
1. Go has no super-admin bootstrap tool (Next has scripts/bootstrap-admin.mjs); the Go binary exposes no CLI subcommands.
2. Go has no legacy-account import tool (Next has scripts/import-legacy-accounts.mjs); the DB privilege grants for platform_account_migrations already exist in Go's postgres layer.
3. The ACK migration Job still runs node scripts/migrate-postgres.mjs; Go has no migration runner. Acceptable while the Job keeps shipping Node, but a Go runner is worth deciding before cutover.
Deployment artifacts for the Go workload (Go image, ACK manifests, Ingress routing) are intentionally deferred to the cutover workstream, not missing.