fix: validate server names to allow only single slash (#471) (#476)

## Summary
Added validation to reject server names with multiple slashes, ensuring
consistency between JSON schema pattern and API validation.

  - Count slashes in parseServerName() and reject if > 1
  - Add ErrMultipleSlashesInServerName error constant
  - Add unit tests in validators_test.go
  - Add integration test in publish_test.go

  ## Motivation and Context
Fixes #471. The JSON schema regex pattern `^[^/]+/[^/]+$` only allows a
single slash in server names, but the API validation was not enforcing
this constraint. This inconsistency
allowed invalid server names like `com.example/server/path` to be
published.

  ## How Has This Been Tested?
  - Unit tests added to verify slash validation logic
- Integration tests added to verify the publish endpoint rejects
multi-slash names
- Tested various edge cases: trailing slashes, consecutive slashes,
URL-like paths
  - All existing tests pass

  ## Breaking Changes
None. This change only adds validation to reject previously invalid
server names that shouldn't have been accepted.


## Types of changes
- [x] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update

## Checklist
- [x] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [x] My code follows the repository's style guidelines
- [x] New and existing tests pass locally
- [x] I have added appropriate error handling
- [x] I have added or updated documentation as needed
 
## Additional context
- The fix ensures server names follow the intended format:
`namespace/name` (e.g., `com.example/my-server`)
- This validation aligns the API behavior with the existing JSON schema
regex pattern
- Test coverage includes edge cases like `com.example//server`,
`com.example/server/`, and `a/b/c/d/e/f`
- The error message clearly indicates the issue: "server name cannot
contain multiple slashes"

internal/validators/validators.go

@@ -402,6 +402,12 @@ func parseServerName(serverJSON apiv0.ServerJSON) (string, error) {
 		return "", fmt.Errorf("server name must be in format 'dns-namespace/name' (e.g., 'com.example.api/server')")
 	}
 
+	// Check for multiple slashes - reject if found
+	slashCount := strings.Count(name, "/")
+	if slashCount > 1 {
+		return "", ErrMultipleSlashesInServerName
+	}
+
 	parts := strings.SplitN(name, "/", 2)
 	if len(parts) != 2 || parts[0] == "" || parts[1] == "" {
 		return "", fmt.Errorf("server name must be in format 'dns-namespace/name' with non-empty namespace and name parts")
@@ -504,4 +510,4 @@ func isValidHostForDomain(hostname, publisherDomain string) bool {
 	}
 
 	return false
-}
+}