fix: bind edited PG cell values via text wire format

The frontend commits edited cell values as plain strings (and PK locators as
numbers/booleans), but tokio-postgres' String binds only text-ish types and
i64 only int8, so editing integer/boolean/uuid/jsonb/… columns failed with
'cannot convert between the Rust type and the Postgres type'.

Introduce PgText — a ToSql impl that accepts any Postgres type and writes the
value as UTF-8 in text wire format so the server parses it into the column's
own type. NULL binds as SQL NULL. Adds the bytes crate and unit tests.

desktop/src-tauri/Cargo.lock

@@ -1783,8 +1783,9 @@ dependencies = [
 
 [[package]]
 name = "gridline"
-version = "0.7.10"
+version = "0.7.11"
 dependencies = [
+ "bytes",
  "chrono",
  "deadpool-postgres",
  "indexmap 2.14.0",