Add transport type property to Packages (#340)

<!-- Provide a brief summary of your changes -->

## Motivation and Context
<!-- Why is this change needed? What problem does it solve? -->
The following PR:
* Adds the Transport Type property to Packages. _Even though most
packaged MCP servers are stdio this is not always the case so it's nice
to have the option to specify this for clients._
* Adds a constant for the "stdio" type
* Renames the "streamable" one to "streamable-http" (matching better how
the spec refers to it)
* Updates the seed.file to reflect these changes

## How Has This Been Tested?
<!-- Have you tested this in a real application? Which scenarios were
tested? -->
Locally
## Breaking Changes
<!-- Will users need to update their code or configurations? -->
No
## Types of changes
<!-- What types of changes does your code introduce? Put an `x` in all
the boxes that apply: -->
- [ ] Bug fix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update

## Checklist
<!-- Go over all the following points, and put an `x` in all the boxes
that apply. -->
- [ ] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [ ] My code follows the repository's style guidelines
- [ ] New and existing tests pass locally
- [ ] I have added appropriate error handling
- [ ] I have added or updated documentation as needed

## Additional context
<!-- Add any other context, implementation notes, or design decisions
-->

This was discussed in
https://github.com/modelcontextprotocol/registry/discussions/200

---------

Signed-off-by: Radoslav Dimitrov <radoslav@stacklok.com>

docs/server-json/examples.md

@@ -490,7 +490,7 @@ The `dnx` tool ships with the .NET 10 SDK, starting with Preview 6.
       ]
     },
     {
-      "transport_type": "streamable",
+      "transport_type": "streamable-http",
       "url": "https://mcp.anonymous.modelcontextprotocol.io/http"
     }
   ],

docs/server-json/server.schema.json

@@ -117,6 +117,16 @@
             "dnx"
           ]
         },
+        "transport_type": {
+          "type": "string",
+          "enum": [
+            "streamable-http",
+            "sse",
+            "stdio"
+          ],
+          "description": "Transport protocol type for the package",
+          "example": "stdio"
+        },
         "runtime_arguments": {
           "type": "array",
           "description": "A list of arguments to be passed to the package's runtime command (such as docker or npx). The `runtime_hint` field should be provided when `runtime_arguments` are present.",
@@ -323,8 +333,9 @@
         "transport_type": {
           "type": "string",
           "enum": [
-            "streamable",
-            "sse"
+            "streamable-http",
+            "sse",
+            "stdio"
           ],
           "description": "Transport protocol type",
           "example": "sse"

pkg/model/constants.go

@@ -21,8 +21,9 @@ const (
 
 // Transport Types - supported remote transport protocols
 const (
-	TransportTypeStreamable = "streamable"
-	TransportTypeSSE        = "sse"
+	TransportTypeStreamableHTTP = "streamable-http"
+	TransportTypeSSE            = "sse"
+	TransportTypeStdio          = "stdio"
 )
 
 // Runtime Hints - supported package runtime hints

pkg/model/types.go

@@ -20,6 +20,7 @@ type Package struct {
 	Version              string          `json:"version,omitempty"`
 	FileSHA256           string          `json:"file_sha256,omitempty"`
 	RunTimeHint          string          `json:"runtime_hint,omitempty"`
+	TransportType        string          `json:"transport_type,omitempty"`
 	RuntimeArguments     []Argument      `json:"runtime_arguments,omitempty"`
 	PackageArguments     []Argument      `json:"package_arguments,omitempty"`
 	EnvironmentVariables []KeyValueInput `json:"environment_variables,omitempty"`