feat: 插件自动发现 — plugins.json + 代码生成器

- plugins.json 配置文件列出所有插件及其import路径
- gen_plugins.go 读取配置生成 plugins_gen.go
- main.go 调用 registerPlugins() 替代硬编码列表
- 新增 backend/plugins/ 第三方插件目录
- 插件开发文档: docs/api/plugin-development.md

Co-Authored-By: Claude <noreply@anthropic.com>

backend/ai-core/cmd/gen_plugins.go

@@ -0,0 +1,76 @@
+//go:build ignore
+
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"strings"
+)
+
+type PluginEntry struct {
+	Name        string `json:"name"`
+	Import      string `json:"import"`
+	Struct      string `json:"struct"`
+	Constructor string `json:"constructor,omitempty"`
+}
+
+type PluginConfig struct {
+	Version string        `json:"version"`
+	Plugins []PluginEntry `json:"plugins"`
+}
+
+func main() {
+	data, err := os.ReadFile("../plugins.json")
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "read plugins.json: %v\n", err)
+		os.Exit(1)
+	}
+	var cfg PluginConfig
+	if err := json.Unmarshal(data, &cfg); err != nil {
+		fmt.Fprintf(os.Stderr, "parse plugins.json: %v\n", err)
+		os.Exit(1)
+	}
+
+	var sb strings.Builder
+	sb.WriteString("// Code generated by gen_plugins.go; DO NOT EDIT.\n\n")
+	sb.WriteString("package main\n\n")
+	sb.WriteString("import (\n")
+	sb.WriteString("\tplgSDK \"git.yeij.top/AskaEth/Cyrene-Plugins/sdk\"\n")
+
+	aliases := make(map[string]string)
+	for _, p := range cfg.Plugins {
+		alias := p.Name + "pkg"
+		aliases[p.Name] = alias
+		sb.WriteString(fmt.Sprintf("\t%s \"%s\"\n", alias, p.Import))
+	}
+
+	sb.WriteString(")\n\n")
+	sb.WriteString("func registerPlugins(registry interface{ Register(plgSDK.Tool) error }) {\n")
+
+	for _, p := range cfg.Plugins {
+		alias := aliases[p.Name]
+		if p.Constructor != "" {
+			// Plugins with constructor (e.g. NewFilePlugin(dataDir))
+			if p.Name == "file_ops" || p.Name == "http_request" {
+				sb.WriteString(fmt.Sprintf("\tfor _, t := range %s.%s(nil).Tools() {\n", alias, p.Constructor))
+			} else {
+				sb.WriteString(fmt.Sprintf("\tfor _, t := range %s.%s().Tools() {\n", alias, p.Constructor))
+			}
+		} else {
+			sb.WriteString(fmt.Sprintf("\tfor _, t := range (&%s.%s{}).Tools() {\n", alias, p.Struct))
+		}
+		sb.WriteString("\t\tregistry.Register(t)\n")
+		sb.WriteString("\t}\n")
+	}
+
+	sb.WriteString("}\n")
+
+	outPath := "plugins_gen.go"
+	if err := os.WriteFile(outPath, []byte(sb.String()), 0644); err != nil {
+		fmt.Fprintf(os.Stderr, "write %s: %v\n", outPath, err)
+		os.Exit(1)
+	}
+	fmt.Printf("Generated %s with %d plugins\n", outPath, len(cfg.Plugins))
+}