fix(ui): Match PyCharm project view, matched tags and text weight

- Project widget initials follow IDEA's AvatarUtils.initials ("idea" → "I").
- "Show directories with changed descendants" is off by default, as in IDEA.
- FileEntry gains `excluded`: only excluded folders get the excluded icon and
  dimming; git-ignored ones keep the plain icon and the ignored colour.
- `.github` folders get IDEA's GitHub folder icon.
- Matched tag names are never bold and use their own background
  (MATCHED_TAG_NAME); matched braces are bold in dark schemes only.
- Revert Greyscale antialiasing to `antialiased` for UI and editor; `auto`
  rendered text heavier than PyCharm.

Claude-Session: https://claude.ai/code/session_01SaPPsVPuk6ZTNsoUCNCbMv

src/platform/colorScheme.ts

@@ -121,6 +121,8 @@ const SCHEME_VARS = new Set<string>([
   "--bg-editor-inline",
   "--fg-completion-match",
   "--fg-search-match",
+  "--matched-brace-weight",
+  "--bg-matched-tag",
 ]);
 
 type Vars = Map<string, string>;

src/platform/workflowSettings.ts

@@ -156,7 +156,8 @@ export const DEFAULT_EXTERNAL_TOOL: ExternalToolValid = {
 
 export const DEFAULT_WORKFLOW: WorkflowSettings = {
   vcs: {
-    showDirtyDirectories: true,
+    // IDEA's VcsConfiguration.SHOW_DIRTY_RECURSIVELY is off by default.
+    showDirtyDirectories: false,
     limitHistory: true,
     historyLimit: 1000,
     git: {