new_editor: isolate project panel state and harden runtime reset

new_editor/src/Collections/UIEditorTabStrip.cpp

@@ -1,6 +1,8 @@
 #include <XCEditor/Collections/UIEditorTabStrip.h>
 
 #include <algorithm>
+#include <cctype>
+#include <cstring>
 #include <cmath>
 #include <string>
 #include <utility>
@@ -65,7 +67,55 @@ float ResolveEstimatedLabelWidth(
         return item.desiredHeaderLabelWidth;
     }
 
-    return static_cast<float>(item.title.size()) * ClampNonNegative(metrics.estimatedGlyphWidth);
+    const float baseGlyphWidth = ClampNonNegative(metrics.estimatedGlyphWidth);
+    if (item.title.empty() || baseGlyphWidth <= 0.0f) {
+        return 0.0f;
+    }
+
+    const auto estimateAsciiAdvance = [baseGlyphWidth](unsigned char ch) {
+        if (ch == ' ') {
+            return baseGlyphWidth * 0.55f;
+        }
+        if (std::isdigit(ch) != 0) {
+            return baseGlyphWidth * 1.08f;
+        }
+        if (std::strchr(".,:;!|'`ijlft()[]{}", static_cast<int>(ch)) != nullptr) {
+            return baseGlyphWidth * 0.58f;
+        }
+        if (std::strchr("mwMW@#%&QG", static_cast<int>(ch)) != nullptr) {
+            return baseGlyphWidth * 1.45f;
+        }
+        if (std::isupper(ch) != 0) {
+            return baseGlyphWidth * 1.18f;
+        }
+        if (std::strchr("_-+=/\\\\<>*", static_cast<int>(ch)) != nullptr) {
+            return baseGlyphWidth * 0.88f;
+        }
+        return baseGlyphWidth;
+    };
+
+    float width = 0.0f;
+    for (std::size_t index = 0; index < item.title.size();) {
+        const unsigned char ch = static_cast<unsigned char>(item.title[index]);
+        if (ch < 0x80u) {
+            width += estimateAsciiAdvance(ch);
+            ++index;
+            continue;
+        }
+
+        width += baseGlyphWidth * 1.95f;
+        if ((ch & 0xE0u) == 0xC0u) {
+            index += 2u;
+        } else if ((ch & 0xF0u) == 0xE0u) {
+            index += 3u;
+        } else if ((ch & 0xF8u) == 0xF0u) {
+            index += 4u;
+        } else {
+            ++index;
+        }
+    }
+
+    return width;
 }
 
 float ResolveTabTextTop(