feat: enhance xcodeproj, xcassets, scheme, Info.plist, and entitlements

xcodeproj build settings:
- Add CLANG_ANALYZER_LOCALIZABILITY_NONLOCALIZED for localization checks
- Add GCC_C_LANGUAGE_STANDARD=gnu17 for C language standard
- Add LLVM_LTO=YES for Release link-time optimization
- Add ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS
- Add ENABLE_INCOMING_NETWORK_CONNECTIONS for MCP agent server
- Add ENABLE_PREVIEWS for SwiftUI preview support

xcassets (14 new color sets):
- EditorBackground, SidebarBackground, ConsoleBackground
- KeywordColor, StringColor, CommentColor, TypeColor, NumberColor
- LineNumberColor, ToolbarTint, CurrentLineHighlight
- ErrorHighlight, WarningHighlight
- GitAddedColor, GitModifiedColor, GitDeletedColor
- All with proper light/dark mode variants
- Remove orphan icon_64x64.png and icon_base.png (fixed warnings)

xcscheme:
- Add targeted code coverage for CxIDE target only
- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Adv v- Ad- Ad- Ad- Ad- Ad- ALD_- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Ad- Aunch arg (disabled)

Info.plist:
- Add 12 new document types: C, ObjC, Python, Shell, JS, TS,
  HTML, CSS, YAML, XML, Plain Text, Property List

Entitlements:
- Add network.client and network.server for agent HTTP/WebSocket
- Add files.user-selec- Add files.user-selec- Add filads.read-write
- Add- Add- Add- Add- Aderminal com- Add- Add- Add- Add- Aderminal com- Add- Add- Add- Adrestore workspace state
All 53 tests passing

Assets.xcassets/EditorBackground.colorset/Contents.json

@@ -0,0 +1,38 @@
+{
+  "colors" : [
+    {
+      "color" : {
+        "color-space" : "srgb",
+        "components" : {
+          "alpha" : "1.000",
+          "blue" : "0.976",
+          "green" : "0.969",
+          "red" : "0.969"
+        }
+      },
+      "idiom" : "universal"
+    },
+    {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "color" : {
+        "color-space" : "srgb",
+        "components" : {
+          "alpha" : "1.000",
+          "blue" : "0.141",
+          "green" : "0.118",
+          "red" : "0.110"
+        }
+      },
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}