radicle/node/db: Model SQLite synchronous pragma

The newly introduced enum models the SQLite pragma of the same name.

crates/radicle/src/node/db.rs

@@ -110,6 +110,13 @@ impl Database {
         Ok(self)
     }
 
+    /// Set the `synchronous` pragma.
+    pub fn synchronous(self, synchronous: sqlite_ext::Synchronous) -> Result<Self, Error> {
+        self.db
+            .execute(format!("PRAGMA synchronous = {synchronous};"))?;
+        Ok(self)
+    }
+
     /// Initialize by adding our local node to the database.
     pub fn init<'a>(
         mut self,

crates/radicle/src/node/db/sqlite_ext.rs

@@ -30,3 +30,27 @@ impl std::fmt::Display for JournalMode {
         })
     }
 }
+
+/// Value for a `synchronous` pragma statement.
+/// For a description of all variants please refer to
+/// <https://sqlite.org/pragma.html#pragma_synchronous>.
+#[derive(Debug, Default, Copy, Clone, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub enum Synchronous {
+    EXTRA = 3,
+    #[default]
+    FULL = 2,
+    NORMAL = 1,
+    OFF = 0,
+}
+
+impl std::fmt::Display for Synchronous {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(match self {
+            Self::EXTRA => "EXTRA",
+            Self::FULL => "FULL",
+            Self::NORMAL => "NORMAL",
+            Self::OFF => "OFF",
+        })
+    }
+}