Merge 'Prevent setting of encryption keys if already set' from Gaurav Sarma

Fixes https://github.com/tursodatabase/turso/issues/2883
<img width="867" height="128" alt="Screenshot 2025-09-05 at 10 44 18 PM"
src="https://github.com/user-attachments/assets/54a659ba-
cfe1-4622-939b-c7c31362ee5a" />

Reviewed-by: Pere Diaz Bou <pere-altea@homail.com>
Reviewed-by: Avinash Sajjanshetty (@avinassh)

Closes #2914

core/lib.rs

@@ -2060,6 +2060,11 @@ impl Connection {
         };
         tracing::trace!("setting encryption ctx for connection");
         let pager = self.pager.borrow();
+        if pager.is_encryption_ctx_set() {
+            return Err(LimboError::InvalidArgument(
+                "cannot reset encryption attributes if already set in the session".to_string(),
+            ));
+        }
         pager.set_encryption_context(cipher_mode, key)
     }
 }

core/storage/pager.rs

@@ -2163,6 +2163,10 @@ impl Pager {
         Ok(IOResult::Done(f(header)))
     }
 
+    pub fn is_encryption_ctx_set(&self) -> bool {
+        self.io_ctx.borrow_mut().encryption_context().is_some()
+    }
+
     pub fn set_encryption_context(
         &self,
         cipher_mode: CipherMode,