Deduplicate server JSON structs between publisher and registry (#318)

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

## Motivation and Context
<!-- Why is this change needed? What problem does it solve? -->

The following PR eliminates duplicate struct definitions by migrating
the publisher tool to use canonical types from pkg/model, creating a
single source of truth across the codebase. The publisher tool
previously had its own copies of structs that were duplicated, ie.
ServerJSON, Package, Repository, VersionDetail, EnvironmentVariable,
RuntimeArgument and a few others which was not optimal


**Changes in the PR:**
- Refactored the structs to single canonical types located at pkg/model
- Refactor the implementation to use/build canonical structures directly
  - Remove all duplicate definitions (5 structs eliminated)
- Publisher now uses model.ServerJSON, model.Package, model.Repository,
etc.
- Renamed some of the structs to better reflect their use case, i.e.
ServerJSON instead of ServerDetail
- Fixes an issue where the Remote property was missing from the previous
publisher copy of the Server

**Benefits:**
  - Single source of truth - Schema changes in one place
  - Type safety - Compiler catches mismatches
  - Enhanced validation - Field constraints and bson tags
  - Zero breaking changes - Same CLI interface and JSON output
  - Future-proof - New canonical fields automatically available

Supersedes: #217 and #240

## 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: -->
- [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
<!-- 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
-->

---------

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

internal/database/database.go

@@ -4,7 +4,8 @@ import (
 	"context"
 	"errors"
 
-	"github.com/modelcontextprotocol/registry/internal/model"
+	apiv1 "github.com/modelcontextprotocol/registry/pkg/api/v1"
+	"github.com/modelcontextprotocol/registry/pkg/model"
 )
 
 // Common database errors
@@ -20,16 +21,16 @@ var (
 // Database defines the interface for database operations with extension wrapper architecture
 type Database interface {
 	// List retrieves all ServerRecord entries with optional filtering
-	List(ctx context.Context, filter map[string]any, cursor string, limit int) ([]*model.ServerRecord, string, error)
+	List(ctx context.Context, filter map[string]any, cursor string, limit int) ([]*apiv1.ServerRecord, string, error)
 	// GetByID retrieves a single ServerRecord by its ID
-	GetByID(ctx context.Context, id string) (*model.ServerRecord, error)
+	GetByID(ctx context.Context, id string) (*apiv1.ServerRecord, error)
 	// Publish adds a new server to the database with separated server.json and extensions
 	// The registryMetadata contains metadata determined by the service layer (e.g., is_latest, timestamps)
-	Publish(ctx context.Context, serverDetail model.ServerDetail, publisherExtensions map[string]interface{}, registryMetadata model.RegistryMetadata) (*model.ServerRecord, error)
+	Publish(ctx context.Context, serverDetail model.ServerJSON, publisherExtensions map[string]interface{}, registryMetadata apiv1.RegistryExtensions) (*apiv1.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)
+	UpdateServer(ctx context.Context, id string, serverDetail model.ServerJSON, publisherExtensions map[string]interface{}) (*apiv1.ServerRecord, error)
 	// ImportSeed imports initial data from a seed file
 	ImportSeed(ctx context.Context, seedFilePath string) error
 	// Close closes the database connection