fix(i18n): add missing marketplace.accessDenied and translate calendar form

- Add marketplace.accessDenied to de.json and en.json
- Add 12 calendar form field/action keys to widgets.calendar in both locales
- Replace all hardcoded English strings in calendar-source-form.tsx with t() calls
- Remove locale-detection hack on Cancel button (was comparing t() result to English string)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/web/src/messages/en.json

@@ -124,6 +124,15 @@
       "uploadCta": "Upload picture",
       "uploadSuccess": "Profile picture updated successfully.",
       "uploadError": "Upload failed. Please check the file format and size.",
+      "deleteAvatarCta": "Delete picture",
+      "deleteAvatarSuccess": "Profile picture deleted.",
+      "deleteAvatarError": "Delete failed.",
+      "accentColorLabel": "Accent Color",
+      "accentColorHelp": "Used for buttons, highlights and active elements. Default: #ffed00.",
+      "accentColorSave": "Save color",
+      "accentColorReset": "Reset",
+      "accentColorSuccess": "Accent color saved.",
+      "accentColorError": "Save failed.",
       "ldapManagedNotice": "Your password is managed via the directory (LDAP) and cannot be changed here.",
       "passwordSectionTitle": "Change Password"
     },
@@ -185,13 +194,27 @@
       "connectionSuccess": "Connection successful",
       "connectionError": "Connection failed. Please check the URL and credentials.",
       "addSource": "Add source",
-      "sourceEmpty": "No calendar sources configured. Add a source to display events."
+      "sourceEmpty": "No calendar sources configured. Add a source to display events.",
+      "formFieldName": "Name",
+      "formFieldType": "Type",
+      "formFieldUrl": "URL",
+      "formFieldUsername": "Username",
+      "formFieldPassword": "Password",
+      "formFieldColor": "Color",
+      "formFieldExchangeMode": "Exchange Mode",
+      "formSave": "Save",
+      "formSaving": "Saving...",
+      "formCancel": "Cancel",
+      "formUrlErrorHttps": "URL must use HTTPS protocol",
+      "formUrlErrorInvalid": "Invalid URL format"
     },
     "note": {
       "name": "Notes",
       "description": "Free-text notes with Markdown",
       "defaultTitle": "Note",
-      "autosaveError": "Save failed"
+      "autosaveError": "Save failed",
+      "editMode": "Edit",
+      "viewMode": "Preview"
     },
     "calculator": {
       "name": "Calculator",
@@ -434,6 +457,7 @@
     "backToMarketplace": "Back to Marketplace",
     "detailVersion": "Version {version}",
     "detailStatusActive": "Activated for this tenant",
-    "detailStatusInactive": "Not activated"
+    "detailStatusInactive": "Not activated",
+    "accessDenied": "Access denied"
   }
 }