help: Update "Inbox" instructions for Flutter launch.

Also, updates the options in 'Filter by topic status'
for the web app as "Unmuted topics" has been changed
to "Standard view".

Deletes static/images/help/mobile-expand-more.svg,
static/images/help/mobile-expand-less.svg, and
static/images/help/mobile-inbox-icon.svg as they are
no longer used.

Part of #34748.

help/inbox.md

@@ -35,7 +35,7 @@ In the web app, you can control whether the **Inbox** includes all topics, just
 
 {!go-to-inbox.md!}
 
-1. Select **All topics**, **Unmuted topics**, or **Followed topics** from
+1. Select **All topics**, **Standard view**, or **Followed topics** from
    the dropdown in the upper left of the **inbox** view.
 
 {end_tabs}

help/include/inbox-instructions.md

@@ -8,6 +8,17 @@
    your **inbox** when done (e.g., by using the **back** button in your browser
    or desktop app) to select the next conversation.
 
+{tab|mobile}
+
+1. Tap the **Inbox** (<i class="zulip-icon zulip-icon-inbox mobile-help"></i>)
+   tab in the bottom left corner of the app.
+
+2. Tap on a conversation you're interested in to view it. You can return to
+   your **inbox**  when done (e.g., by using the **back** button) to select
+   the next conversation.
+
+{end_tabs}
+
 !!! tip ""
 
     You can collapse or expand the list of topics in a channel by clicking the
@@ -16,24 +27,3 @@
     or **expand**
     (<i class="zulip-icon zulip-icon-arrow-down icon-collapsed-state"></i>)
     icon to the left of a channel name.
-
-{tab|mobile}
-
-1. Tap the **Inbox**
-   (<img src="/static/images/help/mobile-inbox-icon.svg" alt="inbox" class="help-center-icon"/>)
-   tab in the bottom left corner of the app.
-
-2. Tap on a conversation you're interested in to view it. You can return to
-   **Inbox** when done (e.g., by using the **back* button) to select the next
-   conversation.
-
-!!! tip ""
-
-    You can collapse or expand the list of topics in a channel by tapping the
-    **collapse**
-    (<img src="/static/images/help/mobile-expand-less-icon.svg" alt="inbox" class="help-center-icon"/>)
-    or **expand**
-    (<img src="/static/images/help/mobile-expand-more-icon.svg" alt="inbox" class="help-center-icon"/>)
-    icon to the left of a channel name.
-
-{end_tabs}

static/images/help/mobile-expand-less-icon.svg

@@ -1,4 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="#000000">
-    <path d="M0 0h24v24H0z" fill="none"/>
-    <path d="M12 8l-6 6 1.41 1.41L12 10.83l4.59 4.58L18 14z"/>
-</svg>

static/images/help/mobile-expand-more-icon.svg

@@ -1,4 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="#000000">
-    <path d="M0 0h24v24H0z" fill="none"/>
-    <path d="M16.59 8.59L12 13.17 7.41 8.59 6 10l6 6 6-6z"/>
-</svg>

static/images/help/mobile-inbox-icon.svg

@@ -1,4 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="#6492fd" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="feather feather-inbox">
-    <polyline points="22 12 16 12 14 15 10 15 8 12 2 12"></polyline>
-    <path d="M5.45 5.11L2 12v6a2 2 0 0 0 2 2h16a2 2 0 0 0 2-2v-6l-3.45-6.89A2 2 0 0 0 16.76 4H7.24a2 2 0 0 0-1.79 1.11z"></path>
-</svg>