File input: Fix misleading comment about input type wire format in PipelineCommandBase

## Context

From review feedback on #14882.

## Problem

In `PipelineCommandBase.cs` (around line 909), there is a comment that is misleading about the wire format. The AppHost serializes input types via `input.InputType.ToString()`, which produces PascalCase values like `SecretText`/`File`. No producer in the repo emits hyphenated forms like `secret-text`.

The comment shows hyphenated examples and the `Replace("-", "")` normalization is effectively a no-op for current producers. This can mislead future maintainers about the actual wire format.

## Fix

Correct the comment to reflect the actual PascalCase wire format, and consider whether the `Replace("-", "")` normalization is still needed or should be removed.

## References

- https://github.com/microsoft/aspire/pull/14882#discussion_r3532872706

Open PipelineCommandBase.cs around line 909 and inspect the nearby input.InputType.ToString() serialization. Search repository producers to confirm the emitted PascalCase values; done means the comment matches the wire format and the Replace("-", "") normalization is retained or removed consistently with that evidence.

Written by the indexing model from the issue text.