Show the active state of the composer's Inline code button #282

Problem

The composer's Inline code button never shows its active state.

On 14ab7f9c1:

• CodeButton passes type="code" to the composer ToolbarButton (apps/webapp/src/components/chatroom/components/MessageComposer/components/Toolbar/ToolbarButtons/CodeButton.tsx:19).
• The button checks editor.isActive(type) (apps/webapp/src/components/chatroom/components/MessageComposer/components/ui/Button.tsx:39).
• The composer turns off the StarterKit code mark (apps/webapp/src/components/chatroom/components/MessageComposer/hooks/useTiptapEditor.ts:128). It uses InlineCode instead, whose mark name is inlineCode (extensions/extension-inline-code/src/inline-code.ts:27).

So editor.isActive('code') is always false. On desktop, the Bold button works, because its type matches its mark name. On a phone, the grid's active states are stale for a separate reason, tracked in #269.

Steps to reproduce

1. On desktop, open a channel.
2. Open the insert menu (the + button) and choose Text formatting.
3. Type a word, select it, and choose Inline code.
4. See the word styled as inline code, and the Inline code button not in its active state.

Acceptance criteria

• On desktop, with the caret or the selection inside inline code, the Inline code button shows its active state.
• On desktop, with the caret or the selection outside inline code, it does not.

Agent Brief

Category: bug
Summary: The Inline code button must check the composer's real inline code mark name.

Current behavior:
The Inline code button asks for a mark named code, which the composer does not register.

Desired behavior:
The Inline code button asks for the inlineCode mark. On desktop, its active state then follows the selection. On a phone, it follows once #269 lands.

Key interfaces:

• CodeButton — passes the mark name.
• The composer ToolbarButton — checks editor.isActive().
• InlineCode from the inline code extension — mark name inlineCode.

Out of scope

• The rename of the composer ToolbarButton type prop, tracked in Rename the composer ToolbarButton type prop, and drop two dead send props #271.
• The stale active state in the mobile grid, tracked in Show active state in the mobile format grid #269. On a phone, this fix shows only after that issue lands.

Notes

A scratch harness on 14ab7f9c1 used the composer's StarterKit options, InlineCode, a code block, and Hyperlink. code is not in that schema. For a selection inside inline code, and for a caret inside it, isActive('code') was false and isActive('inlineCode') was true. The steps above were not run in a browser.