[Feature Request]: Add a “Pipeline Outline” side panel to list and search transforms used in the current pipeline

### What would you like to happen?

Description
In Pentaho PDI, there is a side panel that lists all steps/transforms already placed in the transformation/pipeline, allowing users to search by name and quickly navigate to an item on the canvas.
In Apache Hop GUI, navigation currently relies on manual zoom/scroll on the canvas, and there is no searchable “outline” of existing transforms. This becomes a significant usability and productivity issue for medium/large pipelines, especially during maintenance and troubleshooting.

Proposed functionality
Create a “Pipeline Outline” side panel for the currently opened pipeline that provides:

A list of all transforms (name + type/icon), optionally including hops/connections

A search input with instant filtering by name and/or transform type

Clicking an item selects the transform and centers (and optionally zooms) it in the canvas

(Optional) Sorting (name/type) and filters: disabled transforms, unconnected transforms, validation/error markers

Expected benefits

Faster navigation in large pipelines, reducing time spent locating transforms

Lower operational risk (less chance of editing the wrong transform due to visual clutter)

Improved troubleshooting efficiency (quickly jump to key transforms and problem areas)

Smoother migration/adoption for users coming from PDI, reducing friction and training effort

Better overall UX for complex pipelines by providing a clear, structured inventory view

### Issue Priority

Priority: 3

### Issue Component

Component: Hop Gui

Start by locating the Hop Gui pipeline-canvas and transform-selection entry points, then confirm how the current pipeline exposes its transforms. Scope the required list, search, selection, and centering behavior from the proposal before implementation. Done means the outline panel supports the agreed behavior and works for the currently opened pipeline.

Written by the indexing model from the issue text.