feat: improve adaptive theme detection, add seconds-level TimePicker and main-window occlusion auto-hide

[Programmer-MrWang]

Motivation

• Provide seconds-precision UI for the "是否在某时间段" rule and move its layout to a dedicated AXAML view for better maintainability and native UX.
• Fix incorrect color sampling that changed ClassIsland theme emphasis color and made adaptive theme switching unreliable by sampling the application window instead of the relevant screen area.
• Implement a user-toggleable automatic occlusion detector to hide the main window when screen content covers it (to avoid showing sensitive or obstructed content).
• Keep theme color source and emphasis color unchanged while only switching light/dark mode consistently with ClassIsland's theme mode mapping.

Description

• Replaced inline control construction for the in-time-period rule with a new Controls/InTimePeriodRuleSettingsControl.axaml and updated Controls/InTimePeriodRuleSettingsControl.cs to load the AXAML and wire TimePicker events, enabling UseSeconds="True" and preserving hh:mm:ss settings sync.
• Reworked Services/AdaptiveThemeSyncService.cs to sample the current screen area (top/bottom one-fifth) based on main-window vertical placement via GetWindowRect and Screen.FromRectangle, compute average luminance on an 8x grid, and map luminance to ClassIsland-compatible theme modes (0=明亮, 1=黑暗) while only switching light/dark (calling IThemeService.SetTheme(mode, null)) so emphasis/primary colors are not altered.
• Added Services/MainWindowOcclusionAutoHideService.cs that runs every 2 seconds, captures the screen region beneath the main window, runs OCR using Windows OcrEngine to measure recognized character length, and hides/shows the main window (ShowWindow) when character count > 4.
• Added a persistent config field AutoHideMainWindowWhenOccluded to ConfigHandlers/MainConfigData.cs and new UI controls in SettingsPage/MoreFeaturesOptionsSettingsPage.axaml plus event handler in its .axaml.cs to toggle and RefreshNow() the services.
• Registered and lifecycle-managed the new occlusion service in Plugin.cs so it starts/stops with the plugin, and added Microsoft.Windows.SDK.Contracts to SystemTools.csproj to enable Windows OCR API usage.

Testing

• Ran git diff --check which reported no whitespace or index issues and succeeded.
• Attempted dotnet restore in this environment but it failed because dotnet is not available here, so build and runtime validation were not executed.
• No automated unit tests were present or executed as part of this change in the current environment.

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Preserve window handle so auto-hide can restore window

After ShowWindow(handle, SW_HIDE), subsequent ticks reacquire Process.GetCurrentProcess().MainWindowHandle; for hidden windows this value becomes IntPtr.Zero, so execution returns here and never reaches the SW_SHOWNA path. That means once the feature hides the main window, it can no longer automatically show it again when occlusion clears unless some external path reopens it. Keep a stable HWND (or resolve hidden-window HWND via a different API) before hiding so restore logic can still run.

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