feat(jwt): server-side session table with keyId + obfuscated uid claims

Replace the {user_id, ip} claim pair with {keyId, uid}:
- keyId is a 32-byte random id that points to a row in the new
  jwt_sessions table holding the real user id, bound IP, UA hash,
  TokenVersion and expiry.
- uid is the user id encoded through pkg/idcodec; mismatch between
  claim uid and session.UserID trips WAF block on the caller IP.
- identityHandler now rejects unknown/revoked/expired sessions, IP
  drift and stale TokenVersion. Refresh updates session.ExpiresAt.

User.TokenVersion bumps on password change and revokes outstanding
sessions, so a leaked JWT secret alone is no longer enough to forge
a token. JWTSession rows are GC'd every 10 minutes (expired + grace
or revoked >24h). OAuth2 callback shares the same issue path.

Includes regression tests for happy path, mismatched claim uid,
revoked session, TokenVersion bump, IP drift and unknown keyId.

Co-authored-by: cloudcode <cloudcode@users.noreply.github.com>

service/singleton/singleton.go

@@ -94,7 +94,7 @@ func InitDBFromPath(path string) error {
 		model.Notification{}, model.AlertRule{}, model.Service{}, model.NotificationGroupNotification{},
 		model.Cron{}, model.Transfer{}, model.ServerGroupServer{},
 		model.NAT{}, model.DDNSProfile{}, model.NotificationGroupNotification{},
-		model.WAF{}, model.Oauth2Bind{}, model.ServerTransfer{})
+		model.WAF{}, model.Oauth2Bind{}, model.ServerTransfer{}, model.JWTSession{})
 	if err != nil {
 		return err
 	}