feat: .NET 11 - #339

Converts every OneOf<T0,...>/OneOf.Types usage to C# union declarations
(union keyword, LangVersion=preview), the structural-union language
feature shipped in .NET 11 Preview 2.

- Common/Results/Unions.cs: generic Union2<T0,T1>..Union8<..> declarations
  replacing OneOf<T0,...T7>.
- Common/Results/CommonResultCases.cs: Success, Success<T>, NotFound,
  Error, Error<T>, None replacing OneOf.Types.
- Rewrote every .Match/.Switch/.TryPickTx/.AsTx/.IsTx call site to
  switch expressions/statements and `is` patterns, since union
  declarations only expose a Value property plus constructors (no
  generated helper methods).
- Removed the OneOf package reference from Common.csproj and
  Directory.Packages.props.

Note: OpenShock.Common.Results.NotFound/Unauthorized share a name with
inherited ControllerBase.NotFound()/.Unauthorized() methods, so a few
controller files alias the namespace (`using Results = ...`) to
disambiguate bare switch-pattern usage.

Enables the runtime-async feature switch solution-wide so async
methods suspend/resume via the runtime instead of compiler-generated
state machines: cleaner stack traces, better debuggability, lower
overhead. No source changes needed - this only affects codegen.

The generic mcr.microsoft.com/dotnet/sdk:11.0-alpine tag doesn't exist
yet since .NET 11 is still preview; MCR only publishes preview-qualified
tags. Also the runtime stages were still on dotnet/aspnet:10.0-alpine
while the apps target net11.0, a mismatch that builds but crashes at
container startup. Also fix .dockerignore's dev/ pattern to Dev/ to
match the actual (case-sensitive) directory name, so local Postgres
data doesn't leak into the build context.

These files already alias the namespace as `Results`; qualify the bare
Success/NotFound references that relied on the plain using instead of
importing the namespace twice.

…appers

Convert union case marker types from readonly structs to sealed
classes/records so they're stored as plain references in the union's
internal object? slot instead of being boxed, and drop Success<T>/Error<T>
wrappers where the payload type can serve as the case directly. Also
consolidates duplicate marker types (DeviceNotFound, ShockerNotFoundOrNoAccess,
WebsocketClosure) into shared ones and replaces ConfigurationService's
Union3/Union4-based getters with a dedicated ConfigGetResult<T>.

…ern matching

Parse errors were unwrapped via an unchecked (string)result.Value! cast on
the Union2 case, bypassing the union's type safety. Introduce a dedicated
TemplateParseError case type and switch on it directly. Keep the internal
parse logic non-throwing (returns the union) and confine the throw to the
public ParseFromFileOrThrow convenience wrapper used at startup.

…le case

TryVerifyEmailAsync's success case was renamed to the VerifyEmailSuccess
record, but the controller's switch still matched the old tuple-wrapped
Success<(Guid, string, string)> type, breaking the Release build (CS8121)
and failing both the ci-build and CodeQL workflows.

Brings in the Internal.Net package extraction (#325) plus the develop
changes since the last sync (healthcheck endpoint, PeriodicTimer rework,
share/publicshare token permissions, dependabot/action pins).

Conflict resolutions:

* Directory.Packages.props: keep the .NET 11 preview pins
  (Npgsql.EntityFrameworkCore.PostgreSQL, Microsoft.AspNetCore.Mvc.Testing),
  take develop's NRedisStack bump and the new OpenShock.Internal.*
  references. OneOf is dropped -- nothing references it since the union
  refactor.
* Common/Results/Unions.cs: OpenShockProblem now lives in
  OpenShock.Internal.Common.Problems.
* Common/Websocket/WebsockBaseController.cs: keep the union pattern match
  over develop's .AsT1.Value, with develop's new JsonOptions argument on
  WriteAsJsonAsync.
* API/Controller/Account/_Turnstile.cs: drop the now-dead Common.Problems
  and Common.Results usings.

…ntroller

SDK preview.7 rejects `case TIn data:` on a Union3<TIn, ...> with CS8780:
matching a union against a type parameter is ambiguous between the union
instance and its underlying value. Switch on message.Value instead, the
same way LiveControlController already unwraps its JSON union.

The CI workflows install DOTNET_VERSION 11.0.x, which now floats to
preview.7, so this broke the build before the global.json bump.

global.json, the Docker sdk/aspnet base images and
Microsoft.AspNetCore.Mvc.Testing move to 11.0.100-preview.7.26381.103 /
11.0.0-preview.7-alpine3.24.

Npgsql.EntityFrameworkCore.PostgreSQL stays on 11.0.0-preview.6, no
preview.7 has been published yet.

NRedisStack 1.7.2 (pulled in with the develop merge) brings
StackExchange.Redis 3.0.25, whose Delegates.s_getArr reflects over the
private MulticastDelegate._invocationList field. That field is gone on
.NET 11, so the connection-failed handler throws MissingFieldException on
a thread pool thread and aborts the process.

This killed API.IntegrationTests mid-run (exit 134) during Testcontainers
teardown. With the pin the full suite completes: 311 passed, 0 failed.