feat(registries): adopt official MCP registry v0.1 protocol + standardize defaults

Implements the board-decided design for goal MCP-856: adopt the official
Model Context Protocol registry protocol and standardize the shipped default
registries. Resolves GH #566 (Pulse v0beta 410) and #567 (remotes-present
misclassification) by design.

- Official v0.1 parser (internal/registries/official.go): descend the wrapped
  { server, _meta } envelope; skip deleted/deprecated/non-latest by default;
  cursor pagination (bounded) with version=latest + search passthrough;
  versioned User-Agent (#566). Tolerates camelCase + snake_case wire fields.
- Per-entry classification (the #567 root fix): packages[] => stdio (InstallCmd
  set, URL empty), remotes[] => remote (URL set), hybrid => prefer the package
  and keep the remote as ConnectURL. Never "remotes present => remote".
- Curated built-in 'reference' source (reference.go): @modelcontextprotocol
  servers shipped in-binary so the basics stay discoverable offline (servers#3047).
- Default-registry rewire (config.go): add Official (primary, no key) + Reference;
  keep Docker MCP catalog; demote Pulse + Smithery to opt-in RequiresKey; drop
  Azure-demo, mcp.run, mcpstore, Fleur, remote-mcp-servers. Remove their bespoke
  parsers and all constructServerURL URL synthesis.
- Cross-surface consistency regression (server/consistency_official_test.go):
  packages-only => stdio, remotes-only => http identical across REST + CLI.

TDD: golden fixture + parser/classification/pagination/reference unit tests.
Local: build, gofmt, golangci-lint (0 issues), go test ./internal/... -race,
and test-api-e2e.sh (65/65, validated against the live official registry) green.

Related #566
Related #567

Co-Authored-By: Paperclip <noreply@paperclip.ing>

Author: Dumbris

internal/config/config.go

@@ -840,13 +840,22 @@ func DefaultDockerIsolationConfig() *DockerIsolationConfig {
 func DefaultRegistries() []RegistryEntry {
 	return []RegistryEntry{
 		{
-			ID:          "pulse",
-			Name:        "Pulse MCP",
-			Description: "Browse and discover MCP use-cases, servers, clients, and news",
-			URL:         "https://www.pulsemcp.com/",
-			ServersURL:  "https://api.pulsemcp.com/v0beta/servers",
-			Tags:        []string{"verified"},
-			Protocol:    "custom/pulse",
+			ID:          "official",
+			Name:        "Official MCP Registry",
+			Description: "The official Model Context Protocol server registry (zero-config, no key required)",
+			URL:         "https://registry.modelcontextprotocol.io/",
+			ServersURL:  "https://registry.modelcontextprotocol.io/v0.1/servers",
+			Tags:        []string{"verified", "official"},
+			Protocol:    "modelcontextprotocol/registry",
+		},
+		{
+			ID:          "reference",
+			Name:        "Reference Servers",
+			Description: "Curated @modelcontextprotocol reference servers, shipped built-in for offline discovery",
+			URL:         "https://github.com/modelcontextprotocol/servers",
+			ServersURL:  "builtin://reference",
+			Tags:        []string{"verified", "official", "reference"},
+			Protocol:    "builtin/reference",
 		},
 		{
 			ID:          "docker-mcp-catalog",
@@ -858,31 +867,24 @@ func DefaultRegistries() []RegistryEntry {
 			Protocol:    "custom/docker",
 		},
 		{
-			ID:          "fleur",
-			Name:        "Fleur",
-			Description: "Fleur is the app store for Claude",
-			URL:         "https://www.fleurmcp.com/",
-			ServersURL:  "https://raw.githubusercontent.com/fleuristes/app-registry/refs/heads/main/apps.json",
+			ID:          "pulse",
+			Name:        "Pulse MCP",
+			Description: "Browse and discover MCP use-cases, servers, clients, and news (opt-in: requires an API key)",
+			URL:         "https://www.pulsemcp.com/",
+			ServersURL:  "https://api.pulsemcp.com/v0.1/servers",
 			Tags:        []string{"verified"},
-			Protocol:    "custom/fleur",
-		},
-		{
-			ID:          "azure-mcp-demo",
-			Name:        "Azure MCP Registry Demo",
-			Description: "A reference implementation of MCP registry using Azure API Center",
-			URL:         "https://demo.registry.azure-mcp.net/",
-			ServersURL:  "https://demo.registry.azure-mcp.net/v0/servers",
-			Tags:        []string{"verified", "demo", "azure", "reference"},
-			Protocol:    "mcp/v0",
+			Protocol:    "custom/pulse",
+			RequiresKey: true,
 		},
 		{
-			ID:          "remote-mcp-servers",
-			Name:        "Remote MCP Servers",
-			Description: "Community-maintained list of remote Model Context Protocol servers",
-			URL:         "https://remote-mcp-servers.com/",
-			ServersURL:  "https://remote-mcp-servers.com/api/servers",
-			Tags:        []string{"verified", "community", "remote"},
-			Protocol:    "custom/remote",
+			ID:          "smithery",
+			Name:        "Smithery",
+			Description: "Smithery MCP server registry (opt-in: requires an API key)",
+			URL:         "https://smithery.ai/",
+			ServersURL:  "https://api.smithery.ai/servers",
+			Tags:        []string{"verified"},
+			Protocol:    "modelcontextprotocol/registry",
+			RequiresKey: true,
 		},
 	}
 }

internal/registries/integration_test.go

@@ -131,7 +131,7 @@ func TestSearchServersIntegration(t *testing.T) {
 
 // TestCompleteWorkflow demonstrates the intended usage pattern
 func TestCompleteWorkflow(t *testing.T) {
-	// Set up default registries (as per user requirements: pulse, docker-mcp-catalog, fleur)
+	// Set up default registries (official + reference, Docker, Pulse opt-in)
 	cfg := config.DefaultConfig()
 	SetRegistriesFromConfig(cfg)
 
@@ -146,8 +146,9 @@ func TestCompleteWorkflow(t *testing.T) {
 			t.Error("expected default registries, got none")
 		}
 
-		// Verify we have the expected default registries (pulse, docker-mcp-catalog, fleur)
-		expectedIDs := []string{"pulse", "docker-mcp-catalog", "fleur"}
+		// Verify we have the expected default registries (official + reference
+		// primary, Docker kept, Pulse opt-in) per MCP-865.
+		expectedIDs := []string{"official", "reference", "docker-mcp-catalog", "pulse"}
 		found := make(map[string]bool)
 
 		for _, reg := range registries {