docs: add dashboard usage overview previews

[alwaysmavs]

Summary

• Reframe the README console preview as a Dashboard preview.
• Split the Dashboard preview into Connector Catalog and Usage Overview sections.
• Add Overview screenshots that show runtime readiness, capability status, usage trends, recent failures, and recent calls.
• Align the Dashboard preview section across English, Simplified Chinese, Japanese, Russian, and French READMEs.

Problem

The README already showed the connector catalog view, but it presented the screenshot as a generic local console preview. That made the Dashboard story less clear and did not show users the usage statistics they can inspect after deploying OpenConnector.

Root Cause

The documentation did not describe the Dashboard as a single product surface with multiple views. The connector catalog and the Overview usage statistics were not presented together, so users could miss that deployed runtimes include both connector browsing and operational usage visibility.

Solution

This PR reorganizes the README Dashboard section around two views: the Connector Catalog for browsing available connectors and the Usage Overview for deployment-time statistics. It adds English and Chinese Overview screenshots, uses the localized screenshots in the English and Chinese READMEs, and uses the English screenshots for the other localized READMEs.

Validation

• npm run fix-check
• git diff --check

[coderabbitai]

Walkthrough

The README.md and localized documentation files (French, Japanese, Russian, Simplified Chinese) had their "Local Console Preview" section replaced with a "Dashboard Preview" section. The new section describes a local Dashboard for browsing connectors, configuring credentials, creating runtime tokens, and inspecting runtime usage, and adds two subsections—"Connector Catalog" and "Usage Overview"—each with corresponding screenshots, replacing the previous single console screenshot.

Possibly related PRs

• oomol-lab/open-connector#31: Updates the same Japanese documentation section replacing local console preview with Dashboard Preview content.
• oomol-lab/open-connector#32: Updates the same Dashboard documentation sections in the French and Russian README files.
• oomol-lab/open-connector#40: Updates the same README preview sections across README.md and translated docs, replacing prior console/preview content with new screenshots.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title is in the required English format and matches the documentation changes.
Description check	✅ Passed	The description clearly matches the README dashboard preview updates across the localized docs.

✨ Finishing Touches

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch codex/add-dashboard-usage-overview

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