aspire integration search is not channel-aware (returns 13.3.5 when CLI is on 13.4 channel)

## Summary

spire integration search (and by extension spire add when no --version is provided) does not appear to be aware of the Aspire release channel the CLI is on. With a 13.4 CLI, both commands return the latest **13.3.5** versions of hosting integrations instead of the 13.4.x versions that should be served from the channel's special feed.

## Repro

CLI version:

+++
aspire --version
# 13.4.0+d8c4e9645a029b4fca8ce20eb00def5526806eda
+++

Searching:

+++
aspire integration search postgres
# Found 4 integration package(s) matching 'postgres'.
# postgresql | Aspire.Hosting.PostgreSQL | 13.3.5
# communitytoolkit-postgresql-extensions | CommunityToolkit.Aspire.Hosting.PostgreSQL.Extensions | 13.3.0
# azure-postgresql | Aspire.Hosting.Azure.PostgreSQL | 13.3.5
# redis | Aspire.Hosting.Redis | 13.3.5

aspire integration search rabbitmq
# rabbitmq | Aspire.Hosting.RabbitMQ | 13.3.5
+++

Adding (no --version):

+++
aspire add postgresql --non-interactive
# ✅ The package Aspire.Hosting.PostgreSQL::13.3.5 was added successfully.

aspire add rabbitmq --non-interactive
# ✅ The package Aspire.Hosting.RabbitMQ::13.3.5 was added successfully.
+++

## Expected

Because the CLI is on the 13.4 channel, spire integration search and spire add (without an explicit --version) should consult the channel-specific feed and return / install **13.4.x** versions of Aspire.Hosting.PostgreSQL, Aspire.Hosting.RabbitMQ, etc.

## Actual

Both commands return / install **13.3.5** — the latest NuGet.org versions — apparently ignoring the channel.

## Impact

- Users on the 13.4 channel silently end up with 13.3.5 hosting integrations and miss bug fixes / features shipped in 13.4 (e.g. for RabbitMQ this affects validation of the 4.3 default image bump and the waiting-dependency surface improvements).
- The mismatch is hard to spot — there is no warning that the integration version doesn't match the CLI channel.

## Notes

- Encountered while running Aspire 13.4 validation, Phase 4 (Postgres + RabbitMQ wired from a TS/Node AppHost).
- spire add --help does not list a channel/feed flag, so there is no obvious user-side workaround other than --version 13.4.x, which requires the user to know the right version a priori.
- Same behavior reproduced for both spire integration search and spire add and across multiple integrations (PostgreSQL, RabbitMQ, Redis, Azure.PostgreSQL).