docs: use public SDK registration in Quickstart

[XnLemon]

Summary

• update English and Chinese Quickstarts to use public SDK Nacos registration
• keep complete Runtime A and Runtime B package main examples aligned with Samples
• clarify Core, SDK, Samples, and endpoint-challenge ownership
• add a local documentation contract test for synchronized, parseable Go blocks and forbidden internal registration imports

Closes #118
Depends on NeKiro-project/nekiro-sdk-go#6 and NeKiro-project/NeKiro-Samples#14.

Validation

• README A/B blocks parse through gofmt
• English and Chinese Go blocks are byte-identical
• formatted blocks match Samples PR [Resolution] Resolve and authorize installed Agent capability #14 Runtime A/B mains
• gofmt -l apps config_center contracts tests docs/usage
• go mod tidy
• go build ./...
• go test -count=1 ./...
• go test -race ./...
• go vet ./...
• git diff --check

No database owner or service behavior changed, so PostgreSQL integration suites are not applicable.

Fallback report

Fallback delta: removed 0, retained 0, added 0, net 0
Added fallback evidence: none

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[XnLemon]

LGTM on current HEAD 6e99b20e0c429f0a8c7ed5c7394be7c7ac1d288d.

I re-reviewed the ownership explanation, both complete Runtime mains, the public registration imports, and the local documentation contract test. English and Chinese Go blocks are byte-identical, parse through gofmt, and their formatted sources match the current Samples PR entrypoints. No required-closure findings remain.

Validation evidence: local Core build/test/race/vet passed; CI quality, contract, PostgreSQL, images, security, Linux/Windows Config Center, Registry, Codecov patch, and required checks are green.

中文

已复核当前 HEAD 6e99b20e0c429f0a8c7ed5c7394be7c7ac1d288d，LGTM。

我重新检查了 owner 说明、两个完整 Runtime main、公共注册包 import，以及本地文档契约测试。英文与中文 Go block 逐字节一致、可通过 gofmt 解析，格式化后与 Samples PR 当前入口一致。没有剩余的 required-closure 问题。

验证证据：本地 Core build/test/race/vet 均通过；CI quality、contract、PostgreSQL、images、security、Linux/Windows Config Center、Registry、Codecov patch 和 required 全绿。

[XnLemon]

LGTM