PR #1 - Refactor: .NET Core -> .NET 10 Upgrade

[AlexanderJohnston]

Summary

This PR upgrades the Totem solution to .NET 10 across the repo to align projects on the same SDK/runtime and unblock continued modernization work.

Key changes

• Updated project target frameworks to .NET 10 (net10.0) where applicable (apps/services/web).
• Updated ASP.NET Core hosting + middleware to be compatible with .NET 10 runtime behavior.
• Updated SignalR wiring to the .NET 10 endpoint routing model (removed reliance on legacy HubRouteBuilder-era types).
• Replaced any legacy Microsoft.AspNetCore.App package references with the appropriate .NET 10 approach (SDK/Web implicit
  framework refs, or FrameworkReference where needed).

Notes / behavior

• This PR is intentionally scoped to framework alignment and “runs on .NET 10” viability. This means that this is a minimum-viability upgrade. Best attempts were made to not alter existing logic or app flows.

Verification

• Start, Stop, Resume all work as expected.
• Queries return as expected.
• Shape of data in the ESDB looks correct.
• Tested on a blank timeline and an existing timeline.

Follow-ups

• Address remaining build warnings (including NuGet vulnerability warnings).
• Continue incremental migration away from legacy MVC routing patterns toward endpoint routing (controllers, routes, etc.).

[AlexanderJohnston]

Please note that during a rebase I accidentally included your last 3 commits. They are showing "authored by bwatts, committed by ajohnston" --> I ran out of mental bandwidth to figure out what was going on there.

I don't think it should cause any issues since there's no movement on the master totem branch but please sanity check!