feat: OpsxDB 桌面数据库客户端首版入库

含工作台/连库多引擎字段与 SSH·SSL、结果编辑、Redis 键浏览、
Tauri 桌面与 docs/落地页；排除本地构建产物与 sidecar 二进制。

apps/server/internal/db/sqlite.go

@@ -0,0 +1,70 @@
+package db
+
+import (
+	"database/sql"
+	"fmt"
+
+	_ "modernc.org/sqlite"
+)
+
+func openSQLite(c ConnReq) (*sql.DB, error) {
+	path := c.Database
+	if path == "" {
+		path = c.Host
+	}
+	if path == "" {
+		return nil, fmt.Errorf("SQLite 需要 database 填文件路径")
+	}
+	return sql.Open("sqlite", path)
+}
+
+func listDatabasesSQLite(_ *sql.DB) ([]string, error) {
+	return []string{"main"}, nil
+}
+
+func listTablesSQLite(db *sql.DB, _ string) ([]string, error) {
+	rows, err := db.Query(`SELECT name FROM sqlite_master WHERE type='table' AND name NOT LIKE 'sqlite_%' ORDER BY 1`)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	out := []string{}
+	for rows.Next() {
+		var name string
+		if err := rows.Scan(&name); err != nil {
+			return nil, err
+		}
+		out = append(out, name)
+	}
+	return out, rows.Err()
+}
+
+func listColumnsSQLite(dbh *sql.DB, _, table string) ([]ColumnInfo, error) {
+	rows, err := dbh.Query(`PRAGMA table_info(` + quotePGIdent(table) + `)`)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var out []ColumnInfo
+	for rows.Next() {
+		var cid int
+		var name, typ string
+		var notnull, pk int
+		var def sql.NullString
+		if err := rows.Scan(&cid, &name, &typ, &notnull, &def, &pk); err != nil {
+			return nil, err
+		}
+		col := ColumnInfo{Name: name, Type: typ, Nullable: notnull == 0}
+		if pk > 0 {
+			col.Key = "PRI"
+		}
+		if def.Valid {
+			col.Default = def.String
+		}
+		out = append(out, col)
+	}
+	if out == nil {
+		out = []ColumnInfo{}
+	}
+	return out, rows.Err()
+}