Theme system overhaul, UI polish, and VS2022 Dark theme

- Replaced hardcoded theme factories with JSON files + CMake build step
- Shared ThemeFieldMeta table for DRY serialization and editor UI
- Fixed live preview (auto-triggers on color change, no toggle button)
- Fixed duplicate theme entries when editing built-in themes
- Moved title bar from icon to bold "Reclass" text with View > Show Icon toggle
- MDI tabs: 24px height, unicode close button styled like TypeSelectorPopup
- Added VS2022 Dark theme with purple accent colors
- Status bar padding, removed monospace font overrides on tabs/statusbar
- Default startup opens Ball demo + Unnamed hex64 tabs

src/themes/defaults/warm.json

@@ -0,0 +1,29 @@
+{
+    "name": "Warm",
+    "background": "#212121",
+    "backgroundAlt": "#2a2a2a",
+    "surface": "#2a2a2a",
+    "border": "#373737",
+    "borderFocused": "#888888",
+    "button": "#373737",
+    "text": "#AAA99F",
+    "textDim": "#7a7a6e",
+    "textMuted": "#555550",
+    "textFaint": "#464646",
+    "hover": "#373737",
+    "selected": "#2d2d2d",
+    "selection": "#21213A",
+    "syntaxKeyword": "#AA9565",
+    "syntaxNumber": "#AAA98C",
+    "syntaxString": "#6B3B21",
+    "syntaxComment": "#464646",
+    "syntaxPreproc": "#AA9565",
+    "syntaxType": "#6B959F",
+    "indHoverSpan": "#AA9565",
+    "indCmdPill": "#2a2a2a",
+    "indDataChanged": "#6B959F",
+    "indHintGreen": "#464646",
+    "markerPtr": "#6B3B21",
+    "markerCycle": "#AA9565",
+    "markerError": "#3C2121"
+}