Convert all web API controllers to TypedResults and add Problem Details middleware

[Copilot]

Convert all controller actions from IActionResult to strongly-typed TypedResults return types per ASP.NET Core 10 guidance, and wire up RFC 7807 Problem Details for automatic error response formatting.

Problem Details middleware

• AddProblemDetails() + UseExceptionHandler() + UseStatusCodePages() in Program.cs
• Unhandled exceptions and bare error status codes now automatically return structured Problem Details JSON

TypedResults conversion (17 controllers)

• All IActionResult returns replaced with concrete types: Ok<T>, NotFound, BadRequest<string>, Accepted<T>, Results<T1, T2>, FileContentHttpResult
• Ok() → TypedResults.Ok(), NotFound() → TypedResults.NotFound(), etc.
• Added global using Microsoft.AspNetCore.Http.HttpResults; to all API project GlobalUsings.cs files

Example

// Before
public async Task<IActionResult> GetHvacZone(string groupName, CancellationToken cancellationToken = default)
{
    var result = await knxQuerySvc.GetHvacZone(groupName, cancellationToken);
    return result is not null ? Ok(result) : NotFound();
}

// After
public async Task<Results<Ok<KnxHvacZone>, NotFound>> GetHvacZone(string groupName, CancellationToken cancellationToken = default)
{
    var result = await knxQuerySvc.GetHvacZone(groupName, cancellationToken);
    return result is not null ? TypedResults.Ok(result) : TypedResults.NotFound();
}

This gives compile-time guarantees on response types and enables better OpenAPI schema generation without relying on [ProducesResponseType] attributes alone.

[f2calv]

Shouldn't TypedResults mean these attributes no longer need to be present?