fix(attdef): SVG dialog buttons, upper-case tags from Properties, Cargo.toml blank line

#1574's dialog drew its pick, close, field and editor buttons with glyph
text (⌖ × ƒ …) that renders as tofu where the font lacks it; they use the
snap and close SVG icons and plain ASCII now. A tag set from Properties is
stored upper case like one from the dialogs, and the stray blank line the
PR left in Cargo.toml is gone.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/entities/attribute.rs

@@ -713,7 +713,7 @@ impl PropertyEditable for AttributeDefinition {
             return;
         }
         match field {
-            "att_tag" => self.tag = value.trim().to_string(),
+            "att_tag" => self.tag = value.trim().to_uppercase(),
             "att_prompt" if !self.flags.constant => self.prompt = value.to_string(),
             "att_default" => {
                 self.default_value = value.to_string();