chore: switch Xcode to the local swift-markdown-engine submodule

Removed the remote XCRemoteSwiftPackageReference and pointed
MarkdownEngine/MarkdownEngineCodeBlocks/MarkdownEngineLatex at the
XCLocalSwiftPackageReference for Vendor/swift-markdown-engine instead.
Package.resolved drops the now-irrelevant remote pin (HighlighterSwift
and SwiftMath stay remote, only swift-markdown-engine itself moved
local).

Also bumps the submodule pointer to include three warning fixes made
directly in the vendored source (var->let, unused local, #selector) —
first real edits to the package now that it's locally editable.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitmodules

@@ -1,3 +1,6 @@
 [submodule "docs/reference/outline-openapi"]
 	path = docs/reference/outline-openapi
 	url = https://github.com/outline/openapi.git
+[submodule "Vendor/swift-markdown-engine"]
+	path = Vendor/swift-markdown-engine
+	url = https://github.com/nodes-app/swift-markdown-engine.git

Outpost.xcodeproj/project.pbxproj

@@ -7,10 +7,10 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		FA7596B230366A1D0000167E /* MarkdownEngine in Frameworks */ = {isa = PBXBuildFile; productRef = FA7596B130366A1D0000167E /* MarkdownEngine */; };
+		FA7596B430366A1D0000167E /* MarkdownEngineCodeBlocks in Frameworks */ = {isa = PBXBuildFile; productRef = FA7596B330366A1D0000167E /* MarkdownEngineCodeBlocks */; };
+		FA7596B630366A1D0000167E /* MarkdownEngineLatex in Frameworks */ = {isa = PBXBuildFile; productRef = FA7596B530366A1D0000167E /* MarkdownEngineLatex */; };
 		FAF99C44302CF1BD00C9949F /* OutlineKit in Frameworks */ = {isa = PBXBuildFile; productRef = FAF99C43302CF1BD00C9949F /* OutlineKit */; };
-		FAF99CAF302D120500C9949F /* MarkdownEngine in Frameworks */ = {isa = PBXBuildFile; productRef = FAF99CAE302D120500C9949F /* MarkdownEngine */; };
-		FAF99CB1302D120500C9949F /* MarkdownEngineCodeBlocks in Frameworks */ = {isa = PBXBuildFile; productRef = FAF99CB0302D120500C9949F /* MarkdownEngineCodeBlocks */; };
-		FAF99CB3302D120500C9949F /* MarkdownEngineLatex in Frameworks */ = {isa = PBXBuildFile; productRef = FAF99CB2302D120500C9949F /* MarkdownEngineLatex */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -59,9 +59,9 @@
 			isa = PBXFrameworksBuildPhase;
 			files = (
 				FAF99C44302CF1BD00C9949F /* OutlineKit in Frameworks */,
-				FAF99CB1302D120500C9949F /* MarkdownEngineCodeBlocks in Frameworks */,
+				FA7596B430366A1D0000167E /* MarkdownEngineCodeBlocks in Frameworks */,
-				FAF99CB3302D120500C9949F /* MarkdownEngineLatex in Frameworks */,
+				FA7596B630366A1D0000167E /* MarkdownEngineLatex in Frameworks */,
-				FAF99CAF302D120500C9949F /* MarkdownEngine in Frameworks */,
+				FA7596B230366A1D0000167E /* MarkdownEngine in Frameworks */,
 			);
 		};
 		FAF99C24302CE96200C9949F /* Frameworks */ = {
@@ -116,9 +116,9 @@
 			name = Outpost;
 			packageProductDependencies = (
 				FAF99C43302CF1BD00C9949F /* OutlineKit */,
-				FAF99CAE302D120500C9949F /* MarkdownEngine */,
+				FA7596B130366A1D0000167E /* MarkdownEngine */,
-				FAF99CB0302D120500C9949F /* MarkdownEngineCodeBlocks */,
+				FA7596B330366A1D0000167E /* MarkdownEngineCodeBlocks */,
-				FAF99CB2302D120500C9949F /* MarkdownEngineLatex */,
+				FA7596B530366A1D0000167E /* MarkdownEngineLatex */,
 			);
 			productName = Outpost;
 			productReference = FAF99C18302CE96100C9949F /* Outpost.app */;
@@ -200,7 +200,7 @@
 			minimizedProjectReferenceProxies = 1;
 			packageReferences = (
 				FAF99C42302CF1BD00C9949F /* XCLocalSwiftPackageReference "OutlineKit" */,
-				FAF99CAD302D120500C9949F /* XCRemoteSwiftPackageReference "swift-markdown-engine" */,
+				FA7596B030366A1D0000167E /* XCLocalSwiftPackageReference "Vendor/swift-markdown-engine" */,
 			);
 			preferredProjectObjectVersion = 77;
 			productRefGroup = FAF99C19302CE96100C9949F /* Products */;
@@ -622,43 +622,33 @@
 /* End XCConfigurationList section */
 
 /* Begin XCLocalSwiftPackageReference section */
+		FA7596B030366A1D0000167E /* XCLocalSwiftPackageReference "Vendor/swift-markdown-engine" */ = {
+			isa = XCLocalSwiftPackageReference;
+			relativePath = "Vendor/swift-markdown-engine";
+		};
 		FAF99C42302CF1BD00C9949F /* XCLocalSwiftPackageReference "OutlineKit" */ = {
 			isa = XCLocalSwiftPackageReference;
 			relativePath = OutlineKit;
 		};
 /* End XCLocalSwiftPackageReference section */
 
-/* Begin XCRemoteSwiftPackageReference section */
-		FAF99CAD302D120500C9949F /* XCRemoteSwiftPackageReference "swift-markdown-engine" */ = {
-			isa = XCRemoteSwiftPackageReference;
-			repositoryURL = "https://github.com/nodes-app/swift-markdown-engine";
-			requirement = {
-				kind = upToNextMajorVersion;
-				minimumVersion = 0.12.0;
-			};
-		};
-/* End XCRemoteSwiftPackageReference section */
-
 /* Begin XCSwiftPackageProductDependency section */
+		FA7596B130366A1D0000167E /* MarkdownEngine */ = {
+			isa = XCSwiftPackageProductDependency;
+			productName = MarkdownEngine;
+		};
+		FA7596B330366A1D0000167E /* MarkdownEngineCodeBlocks */ = {
+			isa = XCSwiftPackageProductDependency;
+			productName = MarkdownEngineCodeBlocks;
+		};
+		FA7596B530366A1D0000167E /* MarkdownEngineLatex */ = {
+			isa = XCSwiftPackageProductDependency;
+			productName = MarkdownEngineLatex;
+		};
 		FAF99C43302CF1BD00C9949F /* OutlineKit */ = {
 			isa = XCSwiftPackageProductDependency;
 			productName = OutlineKit;
 		};
-		FAF99CAE302D120500C9949F /* MarkdownEngine */ = {
-			isa = XCSwiftPackageProductDependency;
-			package = FAF99CAD302D120500C9949F /* XCRemoteSwiftPackageReference "swift-markdown-engine" */;
-			productName = MarkdownEngine;
-		};
-		FAF99CB0302D120500C9949F /* MarkdownEngineCodeBlocks */ = {
-			isa = XCSwiftPackageProductDependency;
-			package = FAF99CAD302D120500C9949F /* XCRemoteSwiftPackageReference "swift-markdown-engine" */;
-			productName = MarkdownEngineCodeBlocks;
-		};
-		FAF99CB2302D120500C9949F /* MarkdownEngineLatex */ = {
-			isa = XCSwiftPackageProductDependency;
-			package = FAF99CAD302D120500C9949F /* XCRemoteSwiftPackageReference "swift-markdown-engine" */;
-			productName = MarkdownEngineLatex;
-		};
 /* End XCSwiftPackageProductDependency section */
 	};
 	rootObject = FAF99C10302CE96100C9949F /* Project object */;

Outpost.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved

@@ -1,5 +1,5 @@
 {
-  "originHash" : "f233fa96f0c6bdcdbf87f726af38f25704f6d46a156a27dfac47541baa63bf97",
+  "originHash" : "4127e8224149bef00a33500e8db49748a735e1c07626f2255faea52554afef5e",
   "pins" : [
     {
       "identity" : "highlighterswift",
@@ -10,15 +10,6 @@
         "version" : "3.1.0"
       }
     },
-    {
-      "identity" : "swift-markdown-engine",
-      "kind" : "remoteSourceControl",
-      "location" : "https://github.com/nodes-app/swift-markdown-engine",
-      "state" : {
-        "revision" : "e5f7607fc4021181056ef7a09dbb7573dc0237d9",
-        "version" : "0.12.0"
-      }
-    },
     {
       "identity" : "swiftmath",
       "kind" : "remoteSourceControl",