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/util/common/url_test.go

@@ -27,3 +27,29 @@ func TestEnsureURLScheme(t *testing.T) {
 		})
 	}
 }
+
+func TestParseRemoteRoutingURLKeepsInlineCompatibility(t *testing.T) {
+	tests := []struct {
+		name       string
+		input      string
+		wantSource string
+		wantRemote bool
+		wantErr    bool
+	}{
+		{name: "deeplink stays inline", input: "happ://routing/onadd/abc"},
+		{name: "plain HTTP stays inline", input: "http://example.com/rules"},
+		{name: "multiline stays inline", input: "https://example.com/rules\nMATCH,PROXY"},
+		{name: "HTTPS source", input: "  https://example.com/rules#ignored  ", wantSource: "https://example.com/rules", wantRemote: true},
+		{name: "uppercase scheme", input: "HTTPS://example.com/rules", wantSource: "https://example.com/rules", wantRemote: true},
+		{name: "credentials rejected", input: "https://user:pass@example.com/rules", wantRemote: true, wantErr: true},
+		{name: "missing host rejected", input: "https:///rules", wantRemote: true, wantErr: true},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, remote, err := ParseRemoteRoutingURL(tt.input)
+			if got != tt.wantSource || remote != tt.wantRemote || (err != nil) != tt.wantErr {
+				t.Fatalf("got=%q remote=%v err=%v", got, remote, err)
+			}
+		})
+	}
+}