* feat(dashboard): add VS Code Copilot Chat home banner, remove Provider Quota home card
Announce the OmniCopilot extension right below the Kimi sponsor banner on the
dashboard home page (same size/shape, dismissible, no version gate). Also
removes the "pin Provider Quota to home" card and its now-dead settings
toggle — the widget itself, its auto-refresh setting (shared with the
standalone /dashboard/quota page), and its component tests are untouched.
* fix(dashboard): remove now-dead homeWidgets.ts (dead-code gate)
Deleting the AppearanceTab pin-to-home toggle left this file's sole export,
PIN_PROVIDER_QUOTA_TO_HOME_KEY, with zero remaining consumers, which regressed
the dead-code ratchet from 415 to 416. Removing the file restores the exact
baseline count (415).
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Co-authored-by: Xiangzhe <bakryun0718@proton.me>
