Extract safecsv writer for spreadsheet-safe exports

Wrap encoding/csv with formula-safe cell sanitization and
use it from log export streaming.

Signed-off-by: Cursor Agent <cursoragent@cursor.com>

Co-authored-by: Bryan FRIMIN <bryan@frimin.fr>

pkg/safecsv/writer.go

@@ -0,0 +1,50 @@
+// Copyright (c) 2026 Probo Inc <hello@probo.com>.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package safecsv
+
+import (
+	"encoding/csv"
+	"io"
+)
+
+type Writer struct {
+	inner *csv.Writer
+}
+
+func NewWriter(w io.Writer) *Writer {
+	return &Writer{inner: csv.NewWriter(w)}
+}
+
+func (w *Writer) Write(record []string) error {
+	return w.inner.Write(SanitizeRecord(record))
+}
+
+func (w *Writer) WriteRow(fields ...string) error {
+	return w.Write(fields)
+}
+
+func (w *Writer) Flush() {
+	w.inner.Flush()
+}
+
+func (w *Writer) Error() error {
+	return w.inner.Error()
+}