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/command/cmd/core.rs

@@ -36,6 +36,8 @@ pub struct CmdContext<'a> {
     /// View navigation stacks (for drill back/forward)
     pub view_back_stack: &'a [String],
     pub view_forward_stack: &'a [String],
+    /// Whether the app currently has an active drill snapshot.
+    pub has_drill_state: bool,
     /// Display value at the cursor — works uniformly for pivot and records mode.
     pub display_value: String,
     /// How many data rows/cols fit on screen (for viewport scrolling).