feat(i18n): expand locale coverage to 9 languages

[Jocs]

Summary

• Add 6 new locale packs (zh-TW, es, fr, de, ko, pt) and rename zh → zhCN to align with BCP 47 ('zh-CN').
• Fix two ja.ts strings that had leaked Simplified Chinese ('Image src placeholder' and 'Confirm Text').
• Sync the demo (examples/) and the e2e host (e2e/host/) language switchers to surface all 9 locales; refactor the e2e host's if/else dispatch into a map. Update README + e2e specs.

Breaking change

import { zh } from '@muyajs/core' no longer resolves — use import { zhCN } from '@muyajs/core'. muya.i18n.lang reports 'zh-CN' (not 'zh') after muya.locale(zhCN). The full bundled set is now en, zhCN, zhTW, ja, ko, es, fr, de, pt (plus a newly re-exported ILocale type for consumers registering custom locales).

Translation policy

• Brand/product names kept verbatim (Mermaid, Plantuml, Vega Chart, HTML Block).
• Front Matter left in English where no settled native term exists.
• zh-TW derived from zh-CN with Taiwan-idiom adjustments (e.g. 行內程式碼 over straight S→T 行內代碼, 區塊 over 块).
• I18n.t still falls back to English then to raw key, so partial locales are safe; all 73 keys are present in every shipped locale.

Test plan

• pnpm lint — 0 errors (25 pre-existing warnings)
• pnpm lint:types (turbo) — passes
• pnpm test — 386 tests across 43 files pass
• pnpm check-circular — no circular deps
• pnpm --filter @muyajs/core build — emits lib/types/locales/{en,ja,zh-CN,zh-TW,es,fr,de,ko,pt}.d.ts
• CI e2e (.github/workflows/ci-e2e.yml) — locale-switch + public-api specs updated from 'zh' → 'zh-CN'; the pinyin literal in e2e/tests/typing/ime.spec.ts:284 is intentionally untouched (IME input string, not a locale code)
• Manual: pnpm dev, cycle the <select> through all 9 languages, verify slash menu / format toolbar / image edit placeholder / emoji category labels render in the chosen language

Notes

• Filenames use the BCP 47 tag literally (zh-CN.ts, zh-TW.ts); the JS identifiers are camelCase (zhCN, zhTW) since export const zh-CN is invalid.
• The LOCALES maps in examples/src/main.ts and e2e/host/main.ts are keyed by BCP 47 string and must stay in sync with the <option value> strings in their respective index.html — a comment marks this invariant.
• The pre-existing zh translation 'Symbols': '抽象' was preserved verbatim in zh-CN.ts even though '符号' would be a more accurate rendering of the emoji category; flagging for potential follow-up.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR expands Muya’s built-in i18n support from 3 to 9 bundled locales, aligning Simplified Chinese with BCP 47 (zh-CN) via a zh → zhCN rename, and wiring the demo/e2e host language switchers and e2e assertions to the new locale identifiers.

Changes:

• Added 6 new locale packs (zh-TW, es, fr, de, ko, pt) and renamed the Simplified Chinese export from zh to zhCN (with name: 'zh-CN').
• Updated README and public exports (including re-exporting ILocale) to reflect the new locale surface area.
• Synced demo + e2e host language selectors and updated e2e specs to assert 'zh-CN' instead of 'zh'.

Reviewed changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
README.md	Updates documentation/examples to use zhCN and lists all 9 bundled locales.
packages/core/src/locales/zh-TW.ts	Adds Traditional Chinese (zh-TW) locale resource bundle.
packages/core/src/locales/zh-CN.ts	Renames export to zhCN and updates locale name to zh-CN.
packages/core/src/locales/pt.ts	Adds Portuguese locale resource bundle.
packages/core/src/locales/ko.ts	Adds Korean locale resource bundle.
packages/core/src/locales/ja.ts	Fixes two Japanese strings that were incorrectly in Simplified Chinese.
packages/core/src/locales/index.ts	Re-exports the expanded locale set, including zhCN/zhTW.
packages/core/src/locales/fr.ts	Adds French locale resource bundle.
packages/core/src/locales/es.ts	Adds Spanish locale resource bundle.
packages/core/src/locales/de.ts	Adds German locale resource bundle.
packages/core/src/index.ts	Re-exports ILocale type and the expanded locale exports from the package root.
examples/src/main.ts	Expands demo LOCALES map to 9 locales and switches default locale key to en.
examples/index.html	Updates the demo language <select> to include all 9 locales (using BCP 47 tags).
e2e/tests/smoke/public-api.spec.ts	Updates locale-switch assertion from 'zh' to 'zh-CN'.
e2e/tests/i18n/locale-switch.spec.ts	Updates locale-switch tests/labels to use 'zh-CN'.
e2e/host/main.ts	Refactors locale dispatch from if/else to a locale map and includes all 9 locales.
e2e/host/index.html	Updates the e2e host language <select> to include all 9 locales.

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