Color logic gate pins by logical state (high/low)

[esaruoho]

Summary

• Adds a toggleable "Color Logic Pins by State" option in Other Options (persisted via localStorage, off by default)
• When enabled, logic gate and chip pin leads are colored based on whether the pin voltage is above or below the logic threshold: high pins show in the positive color (green by default), low pins show in the neutral color (gray by default)
• Makes signal propagation visually traceable through logic circuits without affecting the existing voltage-gradient coloring system for wires and non-logic elements

Affected elements

• GateElm (AND, OR, XOR, NAND, NOR, XNOR and all subclasses)
• ChipElm (all digital chips: flip-flops, counters, shift registers, etc.)
• InverterElm
• TriStateElm
• DelayBufferElm

Implementation details

• New CircuitElm.colorLogicPins static boolean field, loaded from localStorage on startup
• New CircuitElm.setLogicPinColor(g, volts, threshold) helper method that either applies logic-state coloring or falls back to the standard setVoltageColor() when the option is disabled
• Each logic element's draw() method uses setLogicPinColor() instead of setVoltageColor() for pin leads, with the element's own threshold (typically highVoltage * 0.5)
• Non-digital ChipElm subclasses (e.g. OpAmpElm) continue to use standard voltage coloring
• No changes to wire coloring or non-logic elements

Test plan

• Open a logic circuit (e.g. any circuit with AND/OR/NOT gates)
• Verify pins display using normal voltage-gradient coloring by default
• Open Other Options, enable "Color Logic Pins by State"
• Verify HIGH pins turn the positive color (green) and LOW pins turn the neutral color (gray)
• Verify digital chips (flip-flops, counters) also show logic-state coloring
• Verify non-logic elements (resistors, capacitors, op-amps) are unaffected
• Verify the setting persists across page reloads (localStorage)
• Verify toggling the option off restores normal voltage coloring

Addresses sharpie7#369.

🤖 Generated with Claude Code

[pfalstad]

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