Limit the value can be set for font weight (#18594)

Closes #18531



This PR limits the range of values that can be set for `FontWeight`.
Since any value less than 1.0 or greater than 999.9 causes Zed to crash
on Windows, I’ve restricted `FontWeight` to this range.

I could apply this constraint only on Windows, but considering the
documentation at https://zed.dev/docs/configuring-zed#buffer-font-weight
indicates that `FontWeight` should be between 100 and 900, I thought it
might be a good idea to apply this restriction in the settings.


Release Notes:

- Changed `ui_font_weight` and `buffer_font_weight` settings to require
values to be between `100` and `950` (inclusive).

---------

Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>

crates/theme/src/settings.rs

@@ -520,6 +520,10 @@ pub fn reset_ui_font_size(cx: &mut AppContext) {
     }
 }
 
+fn clamp_font_weight(weight: f32) -> FontWeight {
+    FontWeight(weight.clamp(100., 950.))
+}
+
 impl settings::Settings for ThemeSettings {
     const KEY: Option<&'static str> = None;
 
@@ -579,7 +583,7 @@ impl settings::Settings for ThemeSettings {
                 this.buffer_font.fallbacks = Some(FontFallbacks::from_fonts(value));
             }
             if let Some(value) = value.buffer_font_weight {
-                this.buffer_font.weight = FontWeight(value);
+                this.buffer_font.weight = clamp_font_weight(value);
             }
 
             if let Some(value) = value.ui_font_family.clone() {
@@ -592,7 +596,7 @@ impl settings::Settings for ThemeSettings {
                 this.ui_font.fallbacks = Some(FontFallbacks::from_fonts(value));
             }
             if let Some(value) = value.ui_font_weight {
-                this.ui_font.weight = FontWeight(value);
+                this.ui_font.weight = clamp_font_weight(value);
             }
 
             if let Some(value) = &value.theme {