Add Recycle Bin dashboard widget and Windows query helper

[multiplex55]

Motivation

• Expose Recycle Bin size and item count in the dashboard so users can view and clean it from the UI with the same caching/refresh semantics as other widgets.
• Allow control over automatic refresh frequency and provide a manual header refresh to match other dashboard widgets.

Description

• Added src/dashboard/widgets/recycle_bin.rs implementing RecycleBinWidget with refresh_interval_secs and manual_refresh_only settings, a header Refresh button with tooltip, human-readable size formatting, item count display, and a Clean button that triggers the recycle:clean action.
• Added RecycleBinInfo and query_recycle_bin to src/launcher.rs, using SHQueryRecycleBinW on Windows and returning None on non-Windows targets.
• Extended DashboardDataSnapshot and DashboardDataCache in src/dashboard/data_cache.rs with RecycleBinSnapshot, refresh_recycle_bin, and maybe_refresh_recycle_bin, and wired the recycle-bin refresh into refresh_all and the widget cache flow.
• Registered and exported the new widget in src/dashboard/widgets/mod.rs and wired up its default settings UI factory.

Testing

• Ran cargo fmt to format the changes, which completed successfully.
• No automated unit or integration tests were executed for this PR.

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Codex Task