feat: add Claude API bridge - transparent OpenAI-to-Anthropic protocol conversion

When provider is set to "claude" in config, all OpenAI-compatible API calls
are automatically bridged to Anthropic Claude Messages API, including:

- Non-streaming and streaming chat completions
- Tool calls (function calling) with full bidirectional conversion
- Eino multi-agent via HTTP transport hook (claudeRoundTripper)
- System message extraction, auth header conversion (Bearer → x-api-key)
- SSE stream format conversion (content_block_delta → OpenAI delta)
- TestOpenAI handler support for Claude connectivity testing

Zero impact when provider is "openai" or empty (default behavior unchanged).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/multiagent/runner.go

@@ -19,6 +19,7 @@ import (
 	"cyberstrike-ai/internal/agents"
 	"cyberstrike-ai/internal/config"
 	"cyberstrike-ai/internal/einomcp"
+	"cyberstrike-ai/internal/openai"
 
 	einoopenai "github.com/cloudwego/eino-ext/components/model/openai"
 	"github.com/cloudwego/eino/adk"
@@ -141,6 +142,9 @@ func RunDeepAgent(
 		},
 	}
 
+	// 若配置为 Claude provider，注入自动桥接 transport，对 Eino 透明走 Anthropic Messages API
+	httpClient = openai.NewEinoHTTPClient(&appCfg.OpenAI, httpClient)
+
 	baseModelCfg := &einoopenai.ChatModelConfig{
 		APIKey:     appCfg.OpenAI.APIKey,
 		BaseURL:    strings.TrimSuffix(appCfg.OpenAI.BaseURL, "/"),