Revert "Added an alternative GUI based on JUCE; I like FLTK more..."

This reverts commit cd2f87a8b3.

screenshots/ALL.md

@@ -5,15 +5,6 @@ See [capture notes and reproduction instructions](README.md) for image provenanc
 
 ---
 
-## The optional JUCE workstation
-
-![JUCE workstation playing the bundled test project](juce-workstation.png)
-
-The JUCE frontend plays the bundled test song with an expanded velocity lane;
-missing saved MIDI devices appear as a warning while stereo playback continues.
-
----
-
 ## The xtc workspace at a glance
 
 ![The xtc workspace at a glance](overview.png)

screenshots/README.md

@@ -32,23 +32,6 @@ APIs and GUI history/preparation paths. Original projects, media and user
 configuration are not overwritten. Black margins are the virtual desktop;
 floating views show the actual detached windows together.
 
-## Optional JUCE workstation (Phase 113)
-
-![JUCE workstation playing the bundled test project](juce-workstation.png)
-
-Rendered directly from the actual JUCE component hierarchy, with the first
-track expanded and playback running. The test deliberately configures missing
-MIDI devices and captures finite stereo output through private JACK probe ports.
-It preserves user preferences and physical routes. A running JACK-compatible
-server is required. After building the optional frontend and tests:
-
-```sh
-XTC_JUCE_SCREENSHOT="$PWD/screenshots/juce-workstation.png" \
-  xvfb-run -a -s '-screen 0 1440x960x24' ./build/juce-gui/test_juce_playback
-```
-
-See the [JUCE frontend guide](../src/gui/JUCE/README.md) for SDK and build options.
-
 ## Continuous audio velocity editing (Phase 110)
 
 ![Audio velocity envelope beneath a waveform track](audio-velocity-expanded.png)