fix(records): allow adding rows in empty records view

Add helper methods to CmdContext to clarify layout state and synthetic
record presence. Update AddRecordRow to check for records mode generally
rather than requiring a synthetic record at the current cursor, which
allows adding the first row to an empty records view.

Includes a regression test for the empty records view scenario.

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

src/command/cmd/grid.rs

@@ -443,12 +443,7 @@ impl Cmd for AddRecordRow {
         "add-record-row"
     }
     fn execute(&self, ctx: &CmdContext) -> Vec<Box<dyn Effect>> {
-        let is_records = ctx
-            .cell_key()
-            .as_ref()
-            .and_then(crate::view::synthetic_record_info)
-            .is_some();
-        if !is_records {
+        if !ctx.is_records_mode() {
             return vec![effect::set_status(
                 "add-record-row only works in records mode",
             )];