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/session.go

@@ -0,0 +1,180 @@
+package db
+
+import (
+	"crypto/rand"
+	"database/sql"
+	"encoding/hex"
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/redis/go-redis/v9"
+)
+
+const sessionTTL = 45 * time.Minute
+const maxSessions = 64
+
+type Session struct {
+	ID       string
+	Conn     ConnReq
+	mu       sync.Mutex
+	sqlPool  map[string]*sql.DB
+	redisCli *redis.Client
+	tunnel   *SSHTunnel
+	LastUsed time.Time
+}
+
+var (
+	sessionsMu sync.Mutex
+	sessions   = map[string]*Session{}
+)
+
+func init() {
+	go func() {
+		t := time.NewTicker(2 * time.Minute)
+		defer t.Stop()
+		for range t.C {
+			expireSessions()
+		}
+	}()
+}
+
+func newSessionID() string {
+	var b [16]byte
+	if _, err := rand.Read(b[:]); err != nil {
+		return fmt.Sprintf("%d", time.Now().UnixNano())
+	}
+	return hex.EncodeToString(b[:])
+}
+
+func OpenSession(c ConnReq) (string, error) {
+	c.SQL = ""
+	c.Table = ""
+	c.Key = ""
+	c.Pattern = ""
+	c.SessionID = ""
+
+	dial, tun, err := ApplySSHTunnel(c)
+	if err != nil {
+		return "", err
+	}
+	if err := testDial(dial); err != nil {
+		if tun != nil {
+			tun.Close()
+		}
+		return "", fmt.Errorf("数据库: %w", err)
+	}
+
+	sessionsMu.Lock()
+	if len(sessions) >= maxSessions {
+		sessionsMu.Unlock()
+		if tun != nil {
+			tun.Close()
+		}
+		return "", fmt.Errorf("连接会话已满，请关闭不用的连接后重试")
+	}
+	id := newSessionID()
+	// Persist dialed endpoints (127.0.0.1:local) so later ops reuse the tunnel.
+	stored := dial
+	stored.SSHEnabled = false
+	s := &Session{
+		ID:       id,
+		Conn:     stored,
+		sqlPool:  map[string]*sql.DB{},
+		tunnel:   tun,
+		LastUsed: time.Now(),
+	}
+	sessions[id] = s
+	sessionsMu.Unlock()
+	return id, nil
+}
+
+func GetSession(id string) (*Session, error) {
+	if id == "" {
+		return nil, fmt.Errorf("缺少 sessionId")
+	}
+	sessionsMu.Lock()
+	s, ok := sessions[id]
+	sessionsMu.Unlock()
+	if !ok {
+		return nil, fmt.Errorf("会话已失效，请重新连接")
+	}
+	s.mu.Lock()
+	s.LastUsed = time.Now()
+	s.mu.Unlock()
+	return s, nil
+}
+
+func CloseSession(id string) {
+	sessionsMu.Lock()
+	s, ok := sessions[id]
+	if ok {
+		delete(sessions, id)
+	}
+	sessionsMu.Unlock()
+	if ok {
+		s.closeAll()
+	}
+}
+
+func expireSessions() {
+	cutoff := time.Now().Add(-sessionTTL)
+	sessionsMu.Lock()
+	var dead []*Session
+	for id, s := range sessions {
+		s.mu.Lock()
+		stale := s.LastUsed.Before(cutoff)
+		s.mu.Unlock()
+		if stale {
+			dead = append(dead, s)
+			delete(sessions, id)
+		}
+	}
+	sessionsMu.Unlock()
+	for _, s := range dead {
+		s.closeAll()
+	}
+}
+
+func (s *Session) closeAll() {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	for k, dbh := range s.sqlPool {
+		_ = dbh.Close()
+		delete(s.sqlPool, k)
+	}
+	if s.redisCli != nil {
+		_ = s.redisCli.Close()
+		s.redisCli = nil
+	}
+	if s.tunnel != nil {
+		s.tunnel.Close()
+		s.tunnel = nil
+	}
+}
+
+func (s *Session) ConnFor(req ConnReq) ConnReq {
+	c := s.Conn
+	// SQLite 的 database 是文件路径，对象树里的 "main" 不能覆盖它
+	if req.Database != "" && driverKey(c.Driver) != "sqlite" {
+		c.Database = req.Database
+	}
+	c.SQL = req.SQL
+	c.Table = req.Table
+	c.Key = req.Key
+	c.Pattern = req.Pattern
+	c.Limit = req.Limit
+	c.SessionID = s.ID
+	return c
+}
+
+func ResolveConn(req ConnReq) (ConnReq, error) {
+	if req.SessionID == "" {
+		return req, nil
+	}
+	s, err := GetSession(req.SessionID)
+	if err != nil {
+		return req, err
+	}
+	return s.ConnFor(req), nil
+}