Add Gaahler Metallic Markers pen plugin

[shabo]

Summary

• Adds GaahlerPenPlugin with 10 metallic marker pens based on the Gaahler Metallic Markers set (GM-01 Aluminium through GM-10 Flashy Gold)
• Registers 7 curated drawing sets for different plotting scenarios
• Registers plugin in Register.java component list in alphabetical order

Pen Colors

Code	Name	RGB
GM-01	Aluminium	(200, 200, 200)
GM-02	Stainless Steel	(160, 160, 158)
GM-03	Dark Steel	(105, 105, 100)
GM-04	Dark Iron	(72, 72, 65)
GM-05	Gun Metal	(85, 85, 78)
GM-06	Zirconium Black	(48, 48, 45)
GM-07	Red Copper	(180, 130, 110)
GM-08	Dark Gold	(130, 110, 80)
GM-09	Scorched Gold	(145, 135, 75)
GM-10	Flashy Gold	(195, 175, 85)

Drawing Sets

Set	Pens	Use Case
Metallic Markers	All 10	Full spectrum
Silver Gradient	GM-06 → GM-01	Dark to bright silver sweep
Gold Gradient	GM-08 → GM-10	Dark gold through copper to flashy gold
Silver to Gold	GM-01, 02, 05, 06, 08, 10	Cool-to-warm metallic transition
Copper Accent on Steel	GM-06, 03, 01, 07 (weighted)	Steel base with copper highlights
Dark Monochrome	GM-06, 04, 05	Dramatic dark plots
Bright Contrast	GM-06, 01, 10	Max contrast — black, silver, gold

The "Copper Accent on Steel" set uses weighted distribution (120/100/80/60) so dark steel dominates and copper appears as an accent.

Where to Buy

Gaahleri Metallic Marker Set (10 colors) — best value at $20.00 / $2.00 per marker from Gundam Planet. Full range from Aluminium through Flashy Gold in one box.

Option	Price	Per-Marker
Gundam Planet set of 10	$20.00	$2.00
Gaahleri Official set of 10	$26.80	$2.68
SprayGunner set of 10	$29.99	$3.00
Start Airbrush x6 (sale)	$12.99	$2.17