Add line-plot mode and GIF export to Parallel Printing tab

Add Parallel Printing Visualization tab

Default travel width to 1/4 of filament width, travel opacity to 0.2

Make G-code parser handle standard and valve-encoded formats

Add animated tube-plot G-code visualization with playback controls

Committing previous changes to README and other files

Add color dropdowns for Travel and Print lines

Preserve camera zoom/orientation on opacity change via uirevision

Add Travel and Print opacity sliders to G-Code visualization

Add 3D G-code tool-path viewer and wire layer_height through gcode pipeline