fix the issue when configuring remote MCP servers, hint for naming

[peterj]

Description

fix the issue when configuring remote MCP servers (use the mcp instead of sse as it tries to do a tls handshake), add a hint for incorrect naming of remote servers + extract the actual errors, instead of showing the JSON.

e.g.:

# Before
Error: failed to publish to registry: unexpected status: 400 Bad Request, {"title":"Bad Request","status":400,"detail":"Failed to create server","errors":[{"message":"remote URL https://servereverything.dev/mcp does not match namespace org/servereverything.dev: invalid namespace format: namespace must use reverse-DNS notation (e.g., \"dev.servereverything\" for servereverything.dev)"}]}

# After

Error: failed to publish to registry: 400 Bad Request: remote URL https://servereverything.dev/mcp does not match namespace org/servereverything.dev: invalid namespace format: namespace must use reverse-DNS notation (e.g., "dev.servereverything" for servereverything.dev)

Change Type

/kind fix

Changelog

fix configuring/running remote MCP servers

[Copilot]

Pull request overview

This PR improves remote MCP server handling in the local agent-gateway configuration and makes CLI/API client errors more human-readable by extracting meaningful messages from Huma-style JSON error responses.

Changes:

• Switch local agent-gateway config generation for remote MCP servers from sse targets to mcp targets (to avoid incorrect TLS-handshake behavior).
• Add reverse-DNS “hint” messaging when remote URL hostnames don’t match an invalid/non-reverse-DNS namespace.
• Extract and display server-provided API error messages (instead of dumping raw JSON) and enhance HTTP status parsing.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
internal/registry/validators/validators.go	Improves namespace/remote URL mismatch errors with a reverse-DNS hint helper.
internal/registry/platforms/local/deployment_adapter_local_platform.go	Builds remote MCP target URLs and emits mcp targets for remote servers.
internal/registry/platforms/local/deployment_adapter_local_platform_test.go	Adds unit tests for remote MCP URL building behavior.
internal/client/client.go	Extracts human-readable API error messages and broadens HTTP status detection.
internal/client/client_test.go	Adds tests for API error extraction and HTTP status parsing.

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[inFocus7]

haven't verified locally but the changes code-wise lgtm, left a comment, but that's about it