feat(cmd): allow direct commit of synthetic records in records mode

Allow synthetic record edits to be applied directly to the model when not
in drill mode, whereas they remain staged in drill state when a drill
snapshot is active. This enables editing of records in plain records view.

Additionally, add validation to prevent creating records with empty
coordinates in both direct commits and when applying staged drill edits.
Includes regression tests for persistence in blank models, drill state
staging, and empty coordinate prevention.

Co-Authored-By: fiddlerwoaroof/git-smart-commit (gemma-4-31B-it-UD-Q4_K_XL.gguf)

src/ui/effect.rs

@@ -458,6 +458,10 @@ impl Effect for ApplyAndClearDrill {
                 };
                 app.model.set_cell(orig_key.clone(), value);
             } else {
+                if new_value.is_empty() {
+                    app.status_msg = "Record coordinates cannot be empty".to_string();
+                    continue;
+                }
                 // Rename a coordinate: remove old cell, insert new with updated coord
                 let value = match app.model.get_cell(orig_key) {
                     Some(v) => v.clone(),