feat(ribbon): contextual Block Editor tab while editing a block

Opening the block editor brings up a Block Editor ribbon tab with
Edit / Save / Discard, Attribute Definition, and the geometric,
dimensional and parameter tools that drive parametric blocks. The tab
is only listed while a block editor session is open, and leaving the
session returns to the tab that was active before.

Refs #509

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

src/i18n.rs

@@ -365,6 +365,7 @@ pub fn ribbon_module_title(id: &str, fallback: &str) -> String {
         "layout" => crate::tr!("ribbon-tab", "layout"),
         "manage" => crate::tr!("ribbon-tab", "manage"),
         "view" => crate::tr!("ribbon-tab", "view"),
+        "block_editor" => crate::tr!("ribbon-tab", "block-editor"),
         _ => fallback.to_string(),
     }
 }