Add remote routing URL support (#6168)

* Add remote routing URL support

* Harden remote routing refresh

* fix(sub): harden remote routing fetch and accept Mihomo src rule flag

Remote routing bytes reach the YAML/JSON parsers from goroutines that run
outside Gin's recovery, so a parser panic on crafted input would take down
the whole panel. Contain it in fetch() (a panic now degrades to a failed
refresh that keeps the last-good value and releases the in-flight slot)
and start the refresh, cache-load and startup-warm goroutines through
common.GoRecover like the other background workers.

The route-graph validator only skipped a trailing no-resolve flag, so a
valid Mihomo rule like IP-CIDR,x,DIRECT,no-resolve,src was rejected as an
unknown target; skip both option flags.

Also deduplicate the HTTPS-source classification into
common.ParseRemoteRoutingURL so the save-time validator and the resolver
can never drift (internal/sub imports internal/web/service, so the copy
existed only to avoid the import cycle), move the test-only
mergeRemoteClashRulesYAML helper into the test file, and trim oversized
comment blocks.

---------

Co-authored-by: Duxxie <yelloduxx@users.noreply.github.com>
Co-authored-by: Sanaei <ho3ein.sanaei@gmail.com>

internal/web/job/remote_routing_job.go

@@ -0,0 +1,31 @@
+package job
+
+import (
+	"github.com/mhsanaei/3x-ui/v3/internal/logger"
+	"github.com/mhsanaei/3x-ui/v3/internal/sub"
+	"github.com/mhsanaei/3x-ui/v3/internal/web/service"
+)
+
+// RemoteRoutingJob keeps remote Happ and Clash/Mihomo routing URLs warm: all
+// network work runs here (cron + startup warm), never in a request handler.
+type RemoteRoutingJob struct {
+	settingService service.SettingService
+}
+
+func NewRemoteRoutingJob() *RemoteRoutingJob {
+	return &RemoteRoutingJob{}
+}
+
+func (j *RemoteRoutingJob) Run() {
+	happ, err := j.settingService.GetSubRoutingRules()
+	if err != nil {
+		logger.Warning("Could not read Happ routing source:", err)
+		return
+	}
+	clash, err := j.settingService.GetSubClashRules()
+	if err != nil {
+		logger.Warning("Could not read Clash routing source:", err)
+		return
+	}
+	sub.RefreshRemoteRoutingSources(happ, clash)
+}