Add Palette Sweep effect for full palette animation across segments

[Copilot]

Adds a new 1D effect that sweeps an entire color palette head-to-tail across a segment, with optional bidirectional (ping-pong) mode.

Changes

• FX.h: Added FX_MODE_PALETTE_SWEEP (ID 218), incremented MODE_COUNT to 219
• FX.cpp: Implemented mode_palette_sweep() with effect registration

Parameters

Parameter	Function
Speed	Animation speed
Scale (Intensity)	Palette repetitions: 0→1/4x, 128→1x, 255→4x
Ping-pong (check1)	Bidirectional sweep vs continuous loop

Implementation

void mode_palette_sweep(void)
{
  // Triangle wave offset for ping-pong mode
  if (pingPong) {
    uint16_t phase = (counter >> 8) & 0x1FF;
    offset = (phase >= 256) ? 511 - phase : phase;
  } else {
    offset = (counter >> 8) & 0xFF;
  }
  
  for (unsigned i = 0; i < SEGLEN; i++) {
    uint16_t paletteIndex = ((i * paletteScale) / SEGLEN + offset) & 0xFF;
    SEGMENT.setPixelColor(i, SEGMENT.color_from_palette(paletteIndex, false, true, 0));
  }
}

Effect metadata: "Palette Sweep@!,Scale,,,,Ping-pong;;!"

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• api.registry.nm1.platformio.org
  • Triggering command: /home/REDACTED/.local/bin/pio pio run -e esp32dev (dns block)
• api.registry.platformio.org
  • Triggering command: /home/REDACTED/.local/bin/pio pio run -e esp32dev (dns block)
• collector.platformio.org
  • Triggering command: /home/REDACTED/.local/bin/pio pio run -e esp32dev (dns block)
• dl.espressif.com
  • Triggering command: /usr/bin/curl curl -sI REDACTED (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

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