add loss-free resistor example circuit (pfalstad#132)

Add an example circuit demonstrating a loss-free resistor (LFR) built
from VCCS and VCVS controlled sources. The LFR presents a resistive
input characteristic while transferring absorbed power losslessly to
its output port, as modeled by Singer (1990). This uses the approach
demonstrated by Paul Falstad in the issue discussion.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: esaruoho

src/com/lushprojects/circuitjs1/public/circuits/lfr.txt

@@ -0,0 +1,25 @@
+$ 1 0.000005 18.278915555614752 57 5 50 5e-11
+213 464 288 528 288 0 2 -(a-b)/1000
+w 464 288 464 240 0
+w 464 240 560 240 0
+w 560 240 560 288 0
+w 464 320 464 368 0
+w 464 368 560 368 0
+w 560 368 560 320 0
+g 464 368 464 400 0 0
+R 464 240 464 176 0 1 40 5 0 0 0.5
+212 624 256 640 256 46 lastoutput\p(a-b)^2/(.0001*1000*(d-c)\p.00000001)*timestep
+c 720 288 720 256 2 0.00009999999999999 2.035051474979456 4.01
+w 624 320 608 320 0
+w 608 320 608 400 0
+w 608 400 720 400 0
+w 720 400 720 288 0
+w 624 352 624 416 0
+w 624 416 784 416 0
+w 784 416 784 256 0
+w 784 256 720 256 0
+w 624 256 560 240 0
+w 624 288 560 320 0
+o 8 64 7 4355 0.0001 0.0001 0 1 0.02500000000000001
+o 10 64 7 4032 0.078125 3.2 0 1 0.0390625
+o 10 64 0 4039 2.5 0.2 1 2 10 3

src/com/lushprojects/circuitjs1/public/setuplist.txt

@@ -436,6 +436,9 @@ ccdiff.txt Current Differentiator
 ccint.txt Current Integrator
 ccitov.txt Current-Controlled Voltage Source
 -
++Loss-Free Resistor
+lfr.txt Loss-Free Resistor
+-
 +Spark Gap
 spark-sawtooth.txt Sawtooth Generator
 tesla.txt Tesla Coil