fix sandbox test API names to match actual registration

- Timer: use global setTimeout() instead of mosis.timer.setTimeout()
- JSON: use json.encode/decode instead of mosis.json
- Crypto: use crypto.sha256 instead of mosis.crypto
- Storage: use fs.read/write with /data/ prefix instead of mosis.fs

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/main/assets/apps/shell/shell.lua

@@ -540,14 +540,14 @@ function testSandboxTimer()
     local status = shell_document:GetElementById("timer-status")
     local results = shell_document:GetElementById("sandbox-results")
 
-    if not mosis or not mosis.timer then
+    if not setTimeout then
         if status then status.inner_rml = "Timer API not available" end
         return
     end
 
     if status then status.inner_rml = "Timer started..." end
 
-    mosis.timer.setTimeout(function()
+    setTimeout(function()
         if status then status.inner_rml = "Timer completed!" end
         if results then results.inner_rml = results.inner_rml .. "\nTimer: PASSED (1 second delay)" end
         showToast("Timer test passed!", "success")
@@ -558,14 +558,14 @@ function testSandboxJSON()
     local status = shell_document:GetElementById("json-status")
     local results = shell_document:GetElementById("sandbox-results")
 
-    if not mosis or not mosis.json then
+    if not json then
         if status then status.inner_rml = "JSON API not available" end
         return
     end
 
     local test_data = {name = "test", value = 42, nested = {a = 1, b = 2}}
-    local encoded = mosis.json.encode(test_data)
+    local encoded = json.encode(test_data)
-    local decoded = mosis.json.decode(encoded)
+    local decoded = json.decode(encoded)
 
     if decoded and decoded.name == "test" and decoded.value == 42 then
         if status then status.inner_rml = "JSON encode/decode: PASSED" end
@@ -581,12 +581,12 @@ function testSandboxCrypto()
     local status = shell_document:GetElementById("crypto-status")
     local results = shell_document:GetElementById("sandbox-results")
 
-    if not mosis or not mosis.crypto then
+    if not crypto then
         if status then status.inner_rml = "Crypto API not available" end
         return
     end
 
-    local hash = mosis.crypto.sha256("test")
+    local hash = crypto.sha256("test")
     if hash and #hash > 0 then
         if status then status.inner_rml = "SHA256: " .. hash:sub(1, 16) .. "..." end
         if results then results.inner_rml = results.inner_rml .. "\nCrypto: PASSED" end
@@ -601,26 +601,28 @@ function testSandboxStorage()
     local status = shell_document:GetElementById("storage-status")
     local results = shell_document:GetElementById("sandbox-results")
 
-    if not mosis or not mosis.fs then
+    if not fs then
         if status then status.inner_rml = "Storage API not available" end
         return
     end
 
     local test_content = "Hello from sandbox test!"
-    local write_ok = mosis.fs.writeFile("test.txt", test_content)
+    local write_ok, write_err = fs.write("/data/test.txt", test_content)
 
     if write_ok then
-        local read_content = mosis.fs.readFile("test.txt")
+        local read_content, read_err = fs.read("/data/test.txt")
         if read_content == test_content then
             if status then status.inner_rml = "Storage read/write: PASSED" end
             if results then results.inner_rml = results.inner_rml .. "\nStorage: PASSED" end
             showToast("Storage test passed!", "success")
         else
-            if status then status.inner_rml = "Storage read: FAILED" end
+            local err_msg = read_err or "content mismatch"
+            if status then status.inner_rml = "Storage read: " .. err_msg end
             showToast("Storage read failed!", "error")
         end
     else
-        if status then status.inner_rml = "Storage write: FAILED" end
+        local err_msg = write_err or "unknown error"
+        if status then status.inner_rml = "Storage write: " .. err_msg end
         showToast("Storage write failed!", "error")
     end
 end