[ety001]

T7-4: Localize steem-js signed-calls + rpc-auth-migration tutorials into 7 locales

Adds the two steem-js signature/migration tutorial pages for all seven locales (zh, ru, fr, de, it, es, ko) — 14 new pages:

• docs/<lc>/tutorials/steem-js/signed-calls.md (from docs/tutorials/steem-js/signed-calls.md)
• docs/<lc>/tutorials/steem-js/rpc-auth-migration.md (from docs/tutorials/steem-js/rpc-auth-migration.md)

Content rules

• Code fences byte-identical to en (highest priority): per-page fence counts match en (signed-calls: 35 fences; rpc-auth-migration: 9) and every fenced line was verified byte-for-byte against the en source across all 14 pages. Only surrounding prose is translated. Source quirks are preserved as-is: the duplicated ## Signed RPC Calls heading, the closure added for the unclosed source-README fence, and the bare assert.equal(...) / expect(...).toBe(...) ellipsis placeholders.
• Terminology: follows each locale's frozen glossary baseline in docs/.vitepress/<lc>-glossary.json (e.g. zh 签名密钥/发布密钥/见证人, ru свидетель/приватный ключ, ko 위트니스/서명 키); first-mention parenthetical annotations per each table's conventions; code identifiers (steem-js, signedCall, signedCallAsync, signatureVerification, condenser_api.*, JSON-RPC, RPC) and method/parameter names stay untranslated.
• Links: sibling tutorial links localized to /<lc>/tutorials/... and API index links to /<lc>/api/..., keeping the .html file-page form used by the en pages. External links untouched.
• Headings: frontmatter title/description translated; explicit #/##/### heading structure preserved 1:1 (heading level sequence verified identical to en on all 14 pages).

Sidebar

config.mts: each locale sidebar gains a Tutorials group (教程 / Обучающие материалы / Tutoriels / Tutorials / Tutorial / Tutoriales / 튜토리얼) containing exactly these two entries, link form matching the en sidebar. Root sidebar untouched.

A narrowly scoped ignoreDeadLinks: [/^\/(zh|ru|fr|de|it|es|ko)\/tutorials\//] is added because the remaining locale steem-js tutorial pages (overview / getting-started / read-api / broadcast) are landing in a separate task branch; until they merge, the localized cross-links inside these two pages legitimately point at pages that do not exist on this branch alone. The pattern exempts only the locale tutorials subtree — en links stay checked strictly.

Verification

• Fence audit: 14/14 pages — fence count equal to en, all fenced content byte-identical.
• Heading/bullet/table structure parity vs en verified programmatically on all 14 pages.
• en sources untouched (no modifications outside docs/<lc>/tutorials/ and config.mts).
• NODE_OPTIONS=--max-old-space-size=8192 pnpm build → exit 0 (build complete in 304s); all 14 rendered HTML pages present under docs/.vitepress/dist/<lc>/tutorials/steem-js/.