Add a status field indicating if a server is deprecated or active (#210)

The following PR adds a new server `status` field to support the status
of servers, like deprecated or active

Details:
* Add status field to server.json schema with 'active' and 'deprecated'
values
* Update OpenAPI spec to include status field in Server responses
* Add ServerStatus enum and field to Go model structs
* Update examples to demonstrate status field usage (`active` and
`deprecated`)

Since this is my first PR there's a good chance I might have missed
something so I'll appreciate any feedback to make this and any PRs in
the future easier for you to review 😃

Fixes: #181

## Motivation and Context
<!-- Why is this change needed? What problem does it solve? -->
The main goal is to have a way for server authors to notify registry
consumers that a server may no longer be maintained and shouldn't be
considered for using.

## How Has This Been Tested?
<!-- Have you tested this in a real application? Which scenarios were
tested? -->

## Breaking Changes
<!-- Will users need to update their code or configurations? -->

## 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. -->
- [x] 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
-->

---------

Signed-off-by: Radoslav Dimitrov <radoslav@stacklok.com>
Co-authored-by: Tadas Antanavicius <tadas@tadasant.com>

docs/server-json/examples.md

@@ -6,6 +6,7 @@
 {
   "name": "io.modelcontextprotocol/brave-search",
   "description": "MCP server for Brave Search API integration",
+  "status": "active",
   "repository": {
     "url": "https://github.com/modelcontextprotocol/servers",
     "source": "github",
@@ -71,6 +72,7 @@ This will essentially instruct the MCP client to execute `dnx Knapcode.SampleMcp
 {
   "name": "io.modelcontextprotocol/filesystem",
   "description": "Node.js server implementing Model Context Protocol (MCP) for filesystem operations.",
+  "status": "active",
   "repository": {
     "url": "https://github.com/modelcontextprotocol/servers",
     "source": "github",
@@ -385,4 +387,37 @@ The `dnx` tool ships with the .NET 10 SDK, starting with Preview 6.
     }
   ]
 }
+```
+
+## Deprecated Server Example
+
+```json
+{
+  "name": "io.legacy/old-weather-server",
+  "description": "Legacy weather server - DEPRECATED: Use weather-v2 instead for new projects",
+  "status": "deprecated",
+  "repository": {
+    "url": "https://github.com/example/old-weather",
+    "source": "github",
+    "id": "legacy-abc123-def456-789012-345678-901234567890"
+  },
+  "version_detail": {
+    "version": "0.9.5"
+  },
+  "packages": [
+    {
+      "registry_name": "npm",
+      "name": "@legacy/old-weather-server",
+      "version": "0.9.5",
+      "environment_variables": [
+        {
+          "name": "WEATHER_API_KEY",
+          "description": "Weather API key",
+          "is_required": true,
+          "is_secret": true
+        }
+      ]
+    }
+  ]
+}
 ```

docs/server-json/schema.json

@@ -60,6 +60,12 @@
           "description": "Human-readable description of the server's functionality",
           "example": "Node.js server implementing Model Context Protocol (MCP) for filesystem operations."
         },
+        "status": {
+          "type": "string",
+          "enum": ["active", "deprecated"],
+          "default": "active",
+          "description": "Server lifecycle status. 'deprecated' indicates the server is no longer recommended for new usage."
+        },
         "repository": {
           "$ref": "#/$defs/Repository"
         },