docs: add German, Simplified Chinese and Japanese READMEs

[mrfandu1]

Summary

The README is currently available only in English. Add complete German,
Simplified Chinese, and Japanese versions so readers can follow the setup and
feature documentation in those languages.

Changes

• Add README.de.md, README.zh-CN.md, and README.ja.md, following the existing English README's section order.
• Put the four-language navigation row directly below the H1 in all four READMEs.
• Preserve the code blocks, tool identifiers, license text, and link destinations. Add explicit anchors so links to translated sections continue to work.

Type

• Documentation

Testing

• Checked each translation against the English source. Automated comparisons confirm all three code blocks, all 16 inline-code spans, the license text, all 76 link destinations, and heading levels are preserved in each translation. All local file and fragment targets resolve.
• git diff --check upstream/main HEAD passes.
• Opened all three rendered READMEs in headless Chromium, followed the language links, and verified the section anchors. Chinese and Japanese text render correctly.
• CI at ff0f9ba passes: backend catalog validation, lint, typecheck, tests and build; frontend lint, typecheck and build. The Docker job is skipped by the existing condition for a manual run. CI reports 20 warnings in unchanged application files.
• No new unit tests are needed for these documentation-only changes.

Checklist

• The changes follow the existing README structure and keep the patch to four README files.
• Local documentation checks and the existing CI jobs described above pass.
• The PR has a descriptive title.

The translations are AI-assisted and checked against the source; further language review is welcome. The CLA is still unsigned and must be completed before merge.

Related Issues

Fixes #600. The languages were reserved in the issue comment.

Chandan

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Claim session: pr-helpcode-ai-anythingmcp-600:0xD136d1b2BF05997A6dB0cCe01a8c56F9f47708d5
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Submission: pending; this pull request is the work artifact.

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[github-actions]

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[github-actions]

👋 Welcome, @mrfandu1, and thanks for opening your first PR on AnythingMCP!

A few quick pointers:

• Make sure CI is green before requesting review (Backend, Frontend, Playwright, CodeQL, Trivy).
• If this is a new adapter, the parametrised catalog.spec.ts test will validate it automatically.
• Sign off your commits if you can — it's not blocking, just nice to have.

Someone from the core team will look at this within ~48h. If you don't hear back, please ping us in Discussions / Q&A.

⭐ While you wait — if you find AnythingMCP useful, a star helps others discover it.

[Copilot]

🟢 Approval recommended

Only a non-blocking German wording nit remains.

Pull request overview

Adds German, Simplified Chinese, and Japanese README translations with consistent navigation and section anchors.

Changes:

• Added three localized README files.
• Added four-language navigation to all READMEs.
• Preserved technical content, links, code blocks, and license text.

File summaries

File	Summary
README.zh-CN.md	Adds Simplified Chinese translation.
README.md	Adds language navigation.
README.ja.md	Adds Japanese translation.
README.de.md	Adds German translation.

Review details

• Files reviewed: 4/4 changed files
• Comments generated: 1
• Review effort level: Lite

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