cyi-box: Memphis-style toolbox admin platform

Go(fun)+SQLite backend, Vue 3 frontend. Modules: dashboard, pay gateway
(Epay-compatible + CDK stock), license/card system (per-app appid, domain
binding), AI memory bank with built-in MCP server (/mcp, FTS5 search,
signed read links), server SSH monitor + terminal + SFTP, proxy pool with
protocol-level alive checks, DB manager (mysql/pg/sqlite + SQL
autocomplete + import/export), disk share, vault (AES-GCM + TOTP),
bookmarks, dev tools.

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

backend/internal/db/embed.go

@@ -0,0 +1,8 @@
+// Package db sqlc 生成层。models.go / queries.sql.go 由 `go tool sqlc generate` 产出，
+// 手写部分只有本文件——把 schema.sql 嵌进来供 store 运行时迁移。
+package db
+
+import _ "embed"
+
+//go:embed schema.sql
+var SchemaDDL string