add sandbox-test app content and test functions

- Add main_content.rml for sandbox-test app with test cards for Timer, JSON, Crypto, Storage
- Add sandbox test functions to shell.lua (testSandboxTimer, testSandboxJSON, etc.)
- Register sandbox-test in builtin_ids and shellNavigateTo paths
- Add sandbox-test styles to shell.rml

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

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

@@ -103,7 +103,8 @@ function shellNavigateTo(app_id)
         browser = "apps/browser/browser_content.rml",
         store = "apps/store/store_content.rml",
         camera = "apps/camera/camera_content.rml",
-        music = "apps/music/music_content.rml"
+        music = "apps/music/music_content.rml",
+        ["sandbox-test"] = "apps/sandbox-test/main_content.rml"
     }
 
     local path = app_paths[app_id]
@@ -488,7 +489,8 @@ function launchDiscoveredApp(package_id)
     local app_id = package_id:gsub("com.mosis.", "")
     local builtin_ids = {
         browser = true, camera = true, contacts = true, dialer = true,
-        messages = true, music = true, settings = true, store = true
+        messages = true, music = true, settings = true, store = true,
+        ["sandbox-test"] = true
     }
 
     if builtin_ids[app_id] then
@@ -532,6 +534,97 @@ function launchDiscoveredApp(package_id)
     return false
 end
 
+-- ===== SANDBOX TEST FUNCTIONS =====
+
+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 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()
+        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")
+    end, 1000)
+end
+
+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 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 decoded = mosis.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
+        if results then results.inner_rml = results.inner_rml .. "\nJSON: PASSED" end
+        showToast("JSON test passed!", "success")
+    else
+        if status then status.inner_rml = "JSON test: FAILED" end
+        showToast("JSON test failed!", "error")
+    end
+end
+
+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 status then status.inner_rml = "Crypto API not available" end
+        return
+    end
+
+    local hash = mosis.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
+        showToast("Crypto test passed!", "success")
+    else
+        if status then status.inner_rml = "Crypto test: FAILED" end
+        showToast("Crypto test failed!", "error")
+    end
+end
+
+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 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)
+
+    if write_ok then
+        local read_content = mosis.fs.readFile("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
+            showToast("Storage read failed!", "error")
+        end
+    else
+        if status then status.inner_rml = "Storage write: FAILED" end
+        showToast("Storage write failed!", "error")
+    end
+end
+
 -- Make shell functions globally available for apps
 _G.showToast = showToast
 _G.showDialog = showDialog
@@ -540,5 +633,9 @@ _G.shellNavigateTo = shellNavigateTo
 _G.shellLaunchApp = shellLaunchApp
 _G.launchDiscoveredApp = launchDiscoveredApp
 _G.populateHomeApps = populateHomeApps
+_G.testSandboxTimer = testSandboxTimer
+_G.testSandboxJSON = testSandboxJSON
+_G.testSandboxCrypto = testSandboxCrypto
+_G.testSandboxStorage = testSandboxStorage
 
 print("[Shell] Shell script loaded")