Portal Pipelines: SVG pipeline icon (#7002)

# Description of Changes

Replaces the chain glyph in the pipelines table with a proper pipeline
icon.

Part of a portal (processor) UI-consistency pass, split into small
focused PRs.

## Before / after

<!-- paste before / after screenshots here -->

---

## Checklist

### General

- [x] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [x] I have performed a self-review of my own code
- [x] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### Translations (if applicable)

- [ ] I ran
[`scripts/counter_translation.py`](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/docs/counter_translation.md)

### UI Changes (if applicable)

- [x] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have run `task check` to verify linters, typechecks, and tests
pass
- [x] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md#7-testing)
for more details.

frontend/editor/src/portal/components/pipelines/PipelinesTable.tsx

@@ -1,5 +1,6 @@
 import { useMemo } from "react";
 import { useTranslation } from "react-i18next";
+import AccountTreeRounded from "@mui/icons-material/AccountTreeRounded";
 import ChevronRightRoundedIcon from "@mui/icons-material/ChevronRightRounded";
 import {
   Chip,
@@ -31,7 +32,7 @@ export function PipelinesTable({ pipelines, onRowClick }: PipelinesTableProps) {
         render: (p) => (
           <div className="portal-pipelines__name-cell">
             <span className="portal-pipelines__pipe-dot" aria-hidden>
-              ⛓
+              <AccountTreeRounded style={{ fontSize: "1.2rem" }} />
             </span>
             <div className="portal-pipelines__name-text">
               <strong>{p.name}</strong>