feat: add admin edit endpoint for server moderation (#315)

## Summary

Implements `PUT /v0/servers/{id}` admin edit endpoint to address part of
issue #182, providing an API-based solution for server moderation
without requiring direct database access.

- **New endpoint**: `PUT /v0/servers/{id}` for editing existing servers
- **Security**: Uses existing JWT auth with `PermissionActionEdit`
permissions
- **Anti-undelete protection**: Added `ServerStatusDeleted` status that
cannot be reverted
- **Full implementation**: Database, service, API, and comprehensive
test coverage

## Key Use Cases

- Mark malicious servers as `deleted` for takedown
- Update server metadata for moderation actions

Related to: https://github.com/modelcontextprotocol/registry/issues/182
(but that is not _done_ yet because we need admins to be able to login
(probably with #283), and need to add docs on how to do the takedown,
and probably guidelines on what we will/won't takedown)

internal/database/database.go

@@ -28,6 +28,8 @@ type Database interface {
 	Publish(ctx context.Context, serverDetail model.ServerDetail, publisherExtensions map[string]interface{}, registryMetadata model.RegistryMetadata) (*model.ServerRecord, error)
 	// UpdateLatestFlag updates the is_latest flag for a specific server record
 	UpdateLatestFlag(ctx context.Context, id string, isLatest bool) error
+	// UpdateServer updates an existing server record with new server details
+	UpdateServer(ctx context.Context, id string, serverDetail model.ServerDetail, publisherExtensions map[string]interface{}) (*model.ServerRecord, error)
 	// ImportSeed imports initial data from a seed file
 	ImportSeed(ctx context.Context, seedFilePath string) error
 	// Close closes the database connection

internal/database/memory.go

@@ -246,6 +246,29 @@ func (db *MemoryDB) UpdateLatestFlag(ctx context.Context, id string, isLatest bo
 	return ErrNotFound
 }
 
+// UpdateServer updates an existing server record with new server details
+func (db *MemoryDB) UpdateServer(ctx context.Context, id string, serverDetail model.ServerDetail, publisherExtensions map[string]interface{}) (*model.ServerRecord, error) {
+	if ctx.Err() != nil {
+		return nil, ctx.Err()
+	}
+
+	db.mu.Lock()
+	defer db.mu.Unlock()
+
+	entry, exists := db.entries[id]
+	if !exists {
+		return nil, ErrNotFound
+	}
+
+	// Update the server details
+	entry.ServerJSON = serverDetail
+	entry.PublisherExtensions = publisherExtensions
+	entry.RegistryMetadata.UpdatedAt = time.Now()
+
+	// Return the updated record
+	return entry, nil
+}
+
 // Close closes the database connection
 // For an in-memory database, this is a no-op
 func (db *MemoryDB) Close() error {

internal/database/postgres.go

@@ -531,6 +531,96 @@ func (db *PostgreSQL) UpdateLatestFlag(ctx context.Context, id string, isLatest
 	return nil
 }
 
+// UpdateServer updates an existing server record with new server details
+func (db *PostgreSQL) UpdateServer(ctx context.Context, id string, serverDetail model.ServerDetail, publisherExtensions map[string]interface{}) (*model.ServerRecord, error) {
+	if ctx.Err() != nil {
+		return nil, ctx.Err()
+	}
+
+	// First check if the server exists
+	_, err := db.GetByID(ctx, id)
+	if err != nil {
+		return nil, err
+	}
+
+	// Start a transaction for atomic updates
+	tx, err := db.conn.Begin(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to begin transaction: %w", err)
+	}
+	defer func() {
+		if rollbackErr := tx.Rollback(ctx); rollbackErr != nil && !errors.Is(rollbackErr, pgx.ErrTxClosed) {
+			log.Printf("Failed to rollback transaction: %v", rollbackErr)
+		}
+	}()
+
+	// Prepare JSON data
+	repositoryJSON, err := json.Marshal(serverDetail.Repository)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal repository: %w", err)
+	}
+
+	packagesJSON, err := json.Marshal(serverDetail.Packages)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal packages: %w", err)
+	}
+
+	remotesJSON, err := json.Marshal(serverDetail.Remotes)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal remotes: %w", err)
+	}
+
+	publisherExtensionsJSON, err := json.Marshal(publisherExtensions)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal publisher extensions: %w", err)
+	}
+
+	now := time.Now()
+
+	// Update servers table
+	serverQuery := `
+		UPDATE servers 
+		SET name = $1, description = $2, status = $3, repository = $4, 
+		    version = $5, packages = $6, remotes = $7, updated_at = $8
+		WHERE id = $9
+	`
+
+	_, err = tx.Exec(ctx, serverQuery,
+		serverDetail.Name,
+		serverDetail.Description,
+		serverDetail.Status,
+		repositoryJSON,
+		serverDetail.VersionDetail.Version,
+		packagesJSON,
+		remotesJSON,
+		now,
+		id,
+	)
+	if err != nil {
+		return nil, fmt.Errorf("failed to update server: %w", err)
+	}
+
+	// Update server_extensions table
+	extQuery := `
+		UPDATE server_extensions 
+		SET updated_at = $1, publisher_extensions = $2
+		WHERE server_id = $3
+	`
+
+	_, err = tx.Exec(ctx, extQuery, now, publisherExtensionsJSON, id)
+	if err != nil {
+		return nil, fmt.Errorf("failed to update server extensions: %w", err)
+	}
+
+	// Commit transaction
+	if err := tx.Commit(ctx); err != nil {
+		return nil, fmt.Errorf("failed to commit transaction: %w", err)
+	}
+
+	// Return the updated record
+	return db.GetByID(ctx, id)
+}
+
 // Close closes the database connection
 func (db *PostgreSQL) Close() error {
 	return db.conn.Close(context.Background())