docs: add launch visuals and feedback links

[savva312]

Summary

• add a real Command Center screenshot and focused use cases to the README
• link a dedicated public feedback Discussion
• add a 1280x640 social-preview asset
• fix production workspace path resolution discovered while capturing the screenshot, so pnpm start serves the bundled UI and root data paths correctly

Verification

• pnpm lint
• pnpm typecheck
• pnpm test (153 tests)
• pnpm build
• production pnpm start browser login and Command Center screenshot
• git diff --check

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Cursor Bugbot has reviewed your changes using default effort and found 1 potential issue.

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