feat(wasm): session stores image_secret for recovery QR generation

crates/relicario-wasm/src/session.rs

@@ -6,12 +6,17 @@ use std::cell::RefCell;
 use std::collections::HashMap;
 use zeroize::Zeroizing;
 
+pub struct SessionData {
+    pub master_key: Zeroizing<[u8; 32]>,
+    pub image_secret: Zeroizing<[u8; 32]>,
+}
+
 thread_local! {
-    static SESSIONS: RefCell<HashMap<u32, Zeroizing<[u8; 32]>>> = RefCell::new(HashMap::new());
+    static SESSIONS: RefCell<HashMap<u32, SessionData>> = RefCell::new(HashMap::new());
     static NEXT_HANDLE: RefCell<u32> = const { RefCell::new(1) };
 }
 
-pub fn insert(key: Zeroizing<[u8; 32]>) -> u32 {
+pub fn insert(master_key: Zeroizing<[u8; 32]>, image_secret: Zeroizing<[u8; 32]>) -> u32 {
     let handle = NEXT_HANDLE.with(|n| {
         let mut n = n.borrow_mut();
         let h = *n;
@@ -19,15 +24,26 @@ pub fn insert(key: Zeroizing<[u8; 32]>) -> u32 {
         if *n == 0 { *n = 1; } // avoid reserving 0 as a valid handle
         h
     });
-    SESSIONS.with(|s| { s.borrow_mut().insert(handle, key); });
+    SESSIONS.with(|s| {
+        s.borrow_mut().insert(handle, SessionData { master_key, image_secret });
+    });
     handle
 }
 
+/// Access the master key for a handle. Preserves original `with` signature for all existing callers.
 pub fn with<F, R>(handle: u32, f: F) -> Option<R>
 where
     F: FnOnce(&Zeroizing<[u8; 32]>) -> R,
 {
-    SESSIONS.with(|s| s.borrow().get(&handle).map(f))
+    SESSIONS.with(|s| s.borrow().get(&handle).map(|d| f(&d.master_key)))
+}
+
+/// Access the image_secret for a handle (used by recovery QR).
+pub fn with_image_secret<F, R>(handle: u32, f: F) -> Option<R>
+where
+    F: FnOnce(&Zeroizing<[u8; 32]>) -> R,
+{
+    SESSIONS.with(|s| s.borrow().get(&handle).map(|d| f(&d.image_secret)))
 }
 
 pub fn remove(handle: u32) -> bool {