Introduce IFilePickerService and move SettingsModal and filter modals to EventLogExpert.Components

[jschick04]

Stacked on #513 — base is jschick/debug-log-filters because three of the moved modals' export paths require IFileSaveService from #513.

Summary

Continues the EventLogExpert.Components library lift. Five remaining MAUI-coupled modals (SettingsModal + four filter modals) move into the non-MAUI Razor library after introducing IFilePickerService to abstract their FilePicker.Default calls.

Changes

• IFilePickerService (EventLogExpert.UI.Interfaces) — new abstraction mirroring IFileSaveService. Two methods: PickAsync(title, extensions): Task<string?> and PickMultipleAsync(title, extensions): Task<IReadOnlyList<string>>. Static FilePickerServiceFileTypes with Json and Database constants.
• MauiFilePickerService (MAUI head) — implementation using MAUI Essentials FilePicker.Default. Wraps both methods in MainThread.InvokeOnMainThreadAsync (mirrors MauiFileSaveService); defensively filters null/empty FullPath and null collection results.
• DI registration in MauiProgram.cs (singleton, beside IFileSaveService).
• Modal refactors — four import handlers replaced with the abstraction; picker calls moved inside their existing try/catch blocks for parity with SettingsModal.
• Modal moves — 12 files (SettingsModal + FilterCacheModal + FilterGroup + FilterGroupModal + FilterGroupSection, plus their .razor.cs and .razor.css companions) move from src/EventLogExpert/Components/Modals/ to src/EventLogExpert.Components/Modals/. Namespaces and razor markup unchanged.

Why MAUI Essentials FilePicker (not native WinUI FileOpenPicker)?

FileOpenPicker has no PickerTitle property (only CommitButtonText), and existing modal UX relies on titled prompts. Save-side stayed native because OneDrive needed DeferUpdates/CompleteUpdates; pick-side has no such requirement.

Validation

• dotnet build src/EventLogExpert.slnx — 0 warnings, 0 errors
• dotnet test src/EventLogExpert.slnx — 1879/1879 pass (19 + 144 + 628 + 1088, unchanged from Add filter, virtualization, and export UI to DebugLogModal and unify file save #513)
• 4-reviewer panel (Claude xhigh, GPT-5.5, GPT-5.3-codex, rubber-duck) clean after duck's three robustness fixes were applied (MainThread wrapping, picker call inside try, defensive null on PickMultipleAsync).

Stack note

After #513 merges (squash), this PR will need a manual rebase onto main and force-push.

[Copilot]

Pull request overview

Note

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Introduces an IFilePickerService abstraction to remove direct MAUI FilePicker.Default usage from modal components, supporting the ongoing lift of modals into the non-MAUI components library.

Changes:

• Added IFilePickerService + shared file-type constants for JSON/database picks.
• Implemented MauiFilePickerService (MainThread-wrapped) and registered it in DI.
• Updated modal import flows to use the new abstraction.

Reviewed changes

Copilot reviewed 7 out of 15 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/EventLogExpert/Services/MauiFilePickerService.cs	Adds MAUI implementation of the new file picker abstraction.
src/EventLogExpert/MauiProgram.cs	Registers IFilePickerService in DI for the MAUI head.
src/EventLogExpert/Components/Modals/SettingsModal.razor.cs	Switches database import to IFilePickerService.
src/EventLogExpert/Components/Modals/Filters/FilterGroupModal.razor.cs	Switches JSON import to IFilePickerService.
src/EventLogExpert/Components/Modals/Filters/FilterGroup.razor.cs	Switches JSON import to IFilePickerService.
src/EventLogExpert/Components/Modals/Filters/FilterCacheModal.razor.cs	Switches JSON import to IFilePickerService.
src/EventLogExpert.UI/Interfaces/IFilePickerService.cs	Adds the new picker abstraction and file-type constants.

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[Copilot]

Pull request overview

Copilot reviewed 7 out of 15 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (1)

src/EventLogExpert.Components/Modals/SettingsModal.razor.cs:201

• The picker call uses PickMultipleAsync, but the picker title says "Please select a database file" (singular). Consider updating the title text to reflect multi-select (e.g., "database file(s)" or "one or more database files") to avoid confusing users.