CmdPal: Improve page exception details for users

[jiripolasek]

Summary of the Pull Request

Show timestamp, HRESULT (hex/decimal), and full Exception.ToString() in the error message. Centralize message generation in a helper class for consistency.

Example:

============================================================
😢 An unexpected error occurred in the 'Open' extension.

Summary:
  Message:    Operation is not valid due to the current state of the object. (inferred from HRESULT 0x80131509)
  Type:       System.Runtime.InteropServices.COMException
  Source:     WinRT.Runtime
  Time:       2025-08-07 15:54:20.4189499
  HRESULT:    0x80131509 (-2146233079)

Stack Trace:
   at WinRT.ExceptionHelpers.<ThrowExceptionForHR>g__Throw|38_0(Int32 hr)
   at ABI.Microsoft.CommandPalette.Extensions.IListPageMethods.GetItems(IObjectReference _obj)
   at Microsoft.CmdPal.Core.ViewModels.ListViewModel.FetchItems()
   at Microsoft.CmdPal.Core.ViewModels.ListViewModel.InitializeProperties()
   at Microsoft.CmdPal.Core.ViewModels.PageViewModel.InitializeAsync()

------------------ Full Exception Details ------------------
System.Runtime.InteropServices.COMException (0x80131509)
   at WinRT.ExceptionHelpers.<ThrowExceptionForHR>g__Throw|38_0(Int32 hr)
   at ABI.Microsoft.CommandPalette.Extensions.IListPageMethods.GetItems(IObjectReference _obj)
   at Microsoft.CmdPal.Core.ViewModels.ListViewModel.FetchItems()
   at Microsoft.CmdPal.Core.ViewModels.ListViewModel.InitializeProperties()
   at Microsoft.CmdPal.Core.ViewModels.PageViewModel.InitializeAsync()

ℹ️ If you need further assistance, please include this information in your support request.
============================================================

PR Checklist

• Closes: CmdPal: add more information to the page exception diagnostic string #41034
• Communication: I've discussed this with core contributors already. If the work hasn't been agreed, this work might be rejected
• Tests: Added/updated and all pass
• Localization: All end-user-facing strings can be localized
• Dev docs: Added/updated
• New binaries: Added on the required places
  • JSON for signing for new binaries
  • WXS for installer for new binaries and localization folder
  • YML for CI pipeline for new test projects
  • YML for signed pipeline
• Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

Validation Steps Performed

I crashed an extension on purpose and read the message.

[zadjii-msft]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[jiripolasek]

Oh, snap. I forgot to include one QoL improvement—especially important when dealing with COM. The commit above will add easy to read, message if there's none. Sorry for wasting builder cycles.