fix(file-format): move Preview/Auto-detect buttons into the tab body

The two helpers used to live in the form toolbar under a 'File Format'
group, which added noise to the already busy header (Match/Create
buttons for accounts/customers/suppliers/purposes plus Load Data are
also there).

They are now native Button fields inside the File Format tab, sitting in
a two-column row directly under the Sample Excel File attach widget:

  [ Sample Excel File: ... ]
  [ Preview Sample ]   [ Auto-detect Columns ]
  [ Format / Column Mappings sections ]

Both buttons are gated by depends_on=sample_file, so they only appear
when there's actually a file to operate on — same gating as before, just
contextually placed next to the upload instead of in the global toolbar.

jey_erp/jey_erp/doctype/bank_statement_importer/bank_statement_importer.js

@@ -18,18 +18,6 @@ frappe.ui.form.on('Bank Statement Importer', {
 	refresh(frm) {
 		BIFileFormat.applySampleHeaders(frm);
 
-		// === File Format helpers — available even on new records since they
-		//     help the user set up the import format from a sample file. ===
-		if (frm.doc.sample_file) {
-			frm.add_custom_button(__('Preview Sample'), () => {
-				BIFileFormat.showPreview(frm);
-			}, __('File Format'));
-
-			frm.add_custom_button(__('Auto-detect Columns'), () => {
-				BIFileFormat.autoDetect(frm);
-			}, __('File Format'));
-		}
-
 		if (frm.is_new()) return;
 
 		// === Load Data (file-based, registry-only) ===
@@ -142,6 +130,14 @@ frappe.ui.form.on('Bank Statement Importer', {
 	header_row(frm) {
 		if (frm.doc.sample_file) BIFileFormat.applySampleHeaders(frm, /*force*/ true);
 	},
+
+	preview_sample_btn(frm) {
+		BIFileFormat.showPreview(frm);
+	},
+
+	auto_detect_btn(frm) {
+		BIFileFormat.autoDetect(frm);
+	},
 });
 
 // ─── File Format helpers ─────────────────────────────────────────────────────

jey_erp/jey_erp/doctype/bank_statement_importer/bank_statement_importer.json

@@ -23,6 +23,10 @@
   "default_territory",
   "file_format_tab",
   "sample_file",
+  "ff_sample_actions_section",
+  "preview_sample_btn",
+  "ff_sample_actions_col",
+  "auto_detect_btn",
   "ff_format_section",
   "header_row",
   "amount_mode",
@@ -169,6 +173,29 @@
    "fieldtype": "Attach",
    "label": "Sample Excel File"
   },
+  {
+   "depends_on": "eval:doc.sample_file",
+   "fieldname": "ff_sample_actions_section",
+   "fieldtype": "Section Break"
+  },
+  {
+   "depends_on": "eval:doc.sample_file",
+   "description": "Show the first 20 data rows from the sample file with mapping status per column.",
+   "fieldname": "preview_sample_btn",
+   "fieldtype": "Button",
+   "label": "Preview Sample"
+  },
+  {
+   "fieldname": "ff_sample_actions_col",
+   "fieldtype": "Column Break"
+  },
+  {
+   "depends_on": "eval:doc.sample_file",
+   "description": "Replace the Column Mappings table with a best-effort guess based on the sample file's headers.",
+   "fieldname": "auto_detect_btn",
+   "fieldtype": "Button",
+   "label": "Auto-detect Columns"
+  },
   {
    "fieldname": "ff_format_section",
    "fieldtype": "Section Break",