issue: selecting a skill from the `/` menu inserts `<@id|label>`, which the backend silently ignores

Before Submitting

• I searched open and closed issues and discussions for an existing report.
• I checked whether this is already fixed on the dev branch or latest source.
• I understand that maintainers want a well-written issue before any code pull request.
• I am using the latest available version of Open WebUI for my install method.
• This is not a security vulnerability.

Installation Method

Docker

Open WebUI Version

v0.11.3

Operating System

ubuntu

Browser

No response

Ollama Version

No response

Summary

Selecting a skill from the / command menu produces a mention tag with @ as the
trigger char. The backend's skill-mention regex accepts only $ and /, so the skill
is never loaded. Because the same regex is what strips the markup, the raw tag also
stays in the message and reaches the model, which then improvises a non-existent
skill protocol. Selecting the same skill from the $ menu works.

Steps to reproduce

1. Create an active skill (e.g. id es).
2. In a chat, type /, pick that skill from the list, add a question, send.
3. Inspect the stored message: it contains <@es|label>.

Expected: the skill's full content is injected (the / path is explicitly
supported — see the ch === '/' ? '$' : ch remap in the serializer).

Root cause

/ is the only mention-producing trigger with a custom command that builds the
node by hand, in src/lib/components/chat/MessageInput.svelte:

char: '/',
command: ({ editor, range, props }) => {
    ...
    .insertContentAt(range, [
        { type: 'mention', attrs: props },
        { type: 'text', text: ' ' }
    ])

### Expected Behavior

**Expected:** the skill's full content is injected (the `/` path is explicitly
supported — see the `ch === '/' ? '$' : ch` remap in the serializer).

### Actual Behavior

**Actual:** nothing is injected, the raw tag is left in the user message, and the
model receives `<@es|label>` as literal text.


### Steps to Reproduce

1. Create an active skill (e.g. id `es`).
2. In a chat, type `/`, pick that skill from the list, add a question, send.
3. Inspect the stored message: it contains `<@es|label>`.

### Logs, Screenshots, and Config

**Root cause**

`/` is the only mention-producing trigger with a custom `command` that builds the
node by hand, in `src/lib/components/chat/MessageInput.svelte`:

```js
char: '/',
command: ({ editor, range, props }) => {
    ...
    .insertContentAt(range, [
        { type: 'mention', attrs: props },
        { type: 'text', text: ' ' }
    ])

### Additional Information

_No response_

Start in src/lib/components/chat/MessageInput.svelte at the / command's custom command and trace how its mention node is serialized, including the ch === '/' ? '$' : ch remap. Reproduce the issue with an active skill, then verify that selecting it from / produces a tag the backend recognizes, injects the skill content, and does not leave raw markup in the stored message.