feat: implement AI plugin calling interface with dedicated endpoints

This commit implements the AI plugin calling logic that enables the main
project to communicate with AI plugins using the existing unified plugin
architecture. AI plugins are treated like other plugins but identified
by categories: ["ai"].

Key implementations:
- Added CallAI and GetAICapabilities RPC methods in server.proto
- Implemented AI plugin calling logic in remote_server.go using existing Query interface
- AI plugins use standard map[string]string parameters: method, model, prompt, config
- Response follows DataResult.Pairs format: content, meta, success, error
- HTTP endpoints: POST /api/v1/ai/generate, GET /api/v1/ai/capabilities/{plugin_name}

AI plugin developers need to:
1. Configure categories: ["ai"] in extension.yaml
2. Implement Query method to handle "ai.generate" and "ai.capabilities"
3. Return standard DataResult format

The implementation maintains full compatibility with existing plugin
architecture while providing AI-specific communication standards.

Author: KariHall619

pkg/runner/monitor/monitor.pb.go

@@ -0,0 +1,100 @@
+/*
+Copyright 2024 API Testing Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+	http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package server
+
+// AI Plugin Communication Interface Standards
+// AI plugins use the existing testing.Loader.Query(map[string]string) interface
+
+// Standard AI plugin communication methods
+const (
+	AIMethodGenerate     = "ai.generate"     // Generate content from prompt
+	AIMethodCapabilities = "ai.capabilities" // Get plugin capabilities
+)
+
+// AI Plugin Query Parameter Standards
+// AI plugins are called using loader.Query(query map[string]string) with these parameters:
+
+// For ai.generate:
+//   - "method": "ai.generate"
+//   - "model":  model identifier (e.g., "gpt-4", "claude")  
+//   - "prompt": the prompt or instruction
+//   - "config": optional JSON configuration string (e.g., `{"temperature": 0.7, "max_tokens": 1000}`)
+
+// For ai.capabilities:
+//   - "method": "ai.capabilities"
+
+// AI Plugin Response Standards
+// AI plugins return response through testing.DataResult.Pairs with these keys:
+
+// For successful ai.generate:
+//   - "content": the generated content
+//   - "meta":    optional JSON metadata string (model info, timing, etc.)
+//   - "success": "true"
+
+// For successful ai.capabilities:
+//   - "capabilities": JSON string containing plugin capabilities
+//   - "models":       JSON array of supported models (fallback if capabilities not available)
+//   - "features":     JSON array of supported features (fallback)
+//   - "description":  plugin description (fallback)
+//   - "version":      plugin version (fallback)
+//   - "success":      "true"
+
+// For errors:
+//   - "error":   error message
+//   - "success": "false"
+
+// Plugin Discovery
+// AI plugins are identified by having "ai" in their categories field:
+//   categories: ["ai"]
+
+// Usage Examples:
+//
+// Get AI plugins:
+//   stores, err := server.GetStores(ctx, &SimpleQuery{Kind: "ai"})
+//
+// Call AI plugin:
+//   loader, err := server.getLoaderByStoreName("my-ai-plugin")
+//   result, err := loader.Query(map[string]string{
+//       "method": "ai.generate",
+//       "model":  "gpt-4", 
+//       "prompt": "Hello world",
+//       "config": `{"temperature": 0.7}`,
+//   })
+//   content := result.Pairs["content"]
+
+// Documentation structures (for reference only, actual types are generated from proto)
+// See server.proto for the actual message definitions:
+//
+// AIRequest fields:
+//   - plugin_name: AI plugin name
+//   - model: Model identifier (e.g., "gpt-4", "claude")
+//   - prompt: The prompt or instruction
+//   - config: JSON configuration string (optional)
+//
+// AIResponse fields:
+//   - content: Generated content
+//   - meta: JSON metadata string (optional)
+//   - success: Whether the call succeeded
+//   - error: Error message if failed
+//
+// AICapabilitiesResponse fields:
+//   - models: Supported models
+//   - features: Supported features
+//   - description: Plugin description
+//   - version: Plugin version
+//   - success: Whether the call succeeded
+//   - error: Error message if failed