disable cloze&math buttons in html mode

Following on from 8a07d3161d
Keeping them active seems to encourage users to experiment:
https://forums.ankiweb.net/t/cloze-deleting-html-svg/11011

ts/editor/ClozeButton.svelte

@@ -5,6 +5,7 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 <script lang="typescript">
     import * as tr from "lib/i18n";
     import { disabledKey } from "components/contextKeys";
+    import { inCodableKey } from "./contextKeys";
 
     import IconButton from "components/IconButton.svelte";
     import WithShortcut from "components/WithShortcut.svelte";
@@ -45,13 +46,15 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 
 <WithShortcut shortcut={"Control+Alt?+Shift+C"} let:createShortcut let:shortcutLabel>
     <WithContext key={disabledKey} let:context={disabled}>
+        <WithContext key={inCodableKey} let:context={inCodable}>
             <IconButton
                 tooltip={`${tr.editingClozeDeletion()} (${shortcutLabel})`}
-            {disabled}
+                disabled={inCodable || disabled}
                 on:click={onCloze}
                 on:mount={createShortcut}
             >
                 {@html bracketsIcon}
             </IconButton>
         </WithContext>
+    </WithContext>
 </WithShortcut>

ts/editor/TemplateButtons.svelte

@@ -82,18 +82,22 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     </ButtonGroupItem>
 
     <ButtonGroupItem id="cloze">
+        <OnlyEditable>
             <ClozeButton />
+        </OnlyEditable>
     </ButtonGroupItem>
 
     <ButtonGroupItem>
         <WithDropdownMenu let:createDropdown let:menuId>
             <WithContext key={disabledKey} let:context={disabled}>
+                <OnlyEditable let:disabled={inCodable}>
                     <IconButton
-                    {disabled}
+                        disabled={disabled || inCodable}
                         on:mount={(event) => createDropdown(event.detail.button)}
                     >
                         {@html functionIcon}
                     </IconButton>
+                </OnlyEditable>
             </WithContext>
 
             <DropdownMenu id={menuId}>