Add IQueryScope and QueryScope for tracking query/observable query performing state

[Copilot]

ViewModels and components had no way to know whether queries or observable queries were in progress, making it impossible to drive loading indicators or disable UI during fetches.

Added

• IQueryScope abstract class — injectable into ViewModels (via withViewModel) to expose isPerforming state across a hierarchy of query scopes, mirroring the existing ICommandScope pattern
• QueryScopeImplementation — counter-based implementation supporting concurrent queries and hierarchical child scope propagation
• QueryScope React component — wraps subtrees to provide a scoped context, with an optional setIsPerforming prop callback (stable via useRef)
• useQueryScope hook — reads the nearest IQueryScope from React context
• Documentation/frontend/react/queries/scope.md — full reference for QueryScope / IQueryScope including React usage, ViewModel injection, hierarchical scopes, and API reference, added to the existing queries/ folder structure

Changed

• useQuery — wraps each query execution with notifyPerformingStarted() / notifyPerformingCompleted() on the active IQueryScope
• useObservableQuery — calls notifyPerformingStarted() when a new subscription is created; calls notifyPerformingCompleted() on first result arrival or subscription teardown (whichever comes first)
• withViewModel — registers the ambient IQueryScope in the ViewModel DI container alongside ICommandScope, enabling constructor injection
• Queries documentation restructured into a queries/ folder (aligned with main branch); scope.md and a Query Scope entry added to the capabilities table and toc.yml

Fixed

• Missing blank lines around headings and fenced code blocks in backend observable queries and paging documentation, introduced during merge conflict resolution

[einari]

@copilot We need to have this documented. Restructure Queries documentation in React a bit - add a folder for Queries, similar to Commands. And then do things a bit similar to what we've done for Commands.

[github-actions]

NuGet packages for this PR, e.g. Cratis.Arc:
https://github.com/cratis/arc/packages/1655206?version=20.10.1-pr2169.456ffb3

[Copilot]

@copilot We need to have this documented. Restructure Queries documentation in React a bit - add a folder for Queries, similar to Commands. And then do things a bit similar to what we've done for Comm...

Done in ef6fa9e. The queries.md has been restructured into a queries/ folder matching the commands/ layout:

• queries/index.md — overview, proxy generation, quick start, result type reference, links to subtopics
• queries/react-usage.md — hooks usage, parameters, paging, sorting, observable query transport
• queries/scope.md — full documentation for the new QueryScope / IQueryScope feature including React usage, ViewModel injection, hierarchical scopes, and the API reference

All cross-references from backend docs, frontend core docs, and other react docs that previously pointed to queries.md have been updated to queries/index.md. Markdownlint passes with zero errors.

[github-actions]

NuGet packages for this PR, e.g. Cratis.Arc:
https://github.com/cratis/arc/packages/1655206?version=20.10.1-pr2169.ef6fa9e

[einari]

@copilot Merge and rebase main in and then fix any conflicts.

[Copilot]

@copilot Merge and rebase main in and then fix any conflicts.

Done in 167bd43. Merged main and resolved all conflicts. Main had already restructured the queries docs into a subfolder with a more comprehensive set of pages — conflicts were path reference updates plus an add/add conflict on index.md and toc.yml. Resolution keeps main's full structure and adds the scope.md entry in the capabilities table and toc.yml. The redundant react-usage.md was removed since main's usage.md covers the same content.

[einari]

@copilot Fix the markdown errors

[Copilot]

@copilot Fix the markdown errors

Fixed in 809db57. The merge conflict resolution had dropped blank lines before headings and fenced code blocks in three backend docs — all 5 markdownlint errors now resolved (0 errors across all 205 docs).