Native support for NXP LPC8xx (LPC845-BRK, LPCXpresso804, LPCXpresso845-MAX) #513

Request

Add native fbuild support for the three NXP LPC8xx Cortex-M0+ boards in the ArduinoCore-LPC8xx package:

Why

LPC8xx is a popular cheap Cortex-M0+ family (LPC804 ships at ~$1) with FastLED-relevant peripherals (SPI0, SCT/CTimer PWM, PININT). FastLED smoke examples already exist in the core repo (FastLEDClocklessSmoke, FastLEDSpiSmoke), gated by LPC8XX_ENABLE_FASTLED_EXAMPLE. There's no PlatformIO platform for LPC8xx today, so fbuild users have to drop a custom platformio.ini that overrides platform_packages on top of nxplpc.

What's already in place

The ArduinoCore-LPC8xx repo now ships:

• boards/lpc845brk.json, boards/lpcxpresso804.json, boards/lpcxpresso845max.json — PlatformIO board manifests mirroring boards.txt
• A sample platformio.ini in the README that drives all three envs via platform_packages = framework-arduino-lpc8xx @ https://github.com/zackees/ArduinoCore-LPC8xx.git#main

Reference PR adding those: https://github.com/zackees/ArduinoCore-LPC8xx (PR link will follow in a comment).

Proposed scope

• Recognize lpc845brk, lpcxpresso804, lpcxpresso845max as first-class fbuild targets.
• Wire the Arduino core override above (or vendor it) so users don't need a hand-rolled platformio.ini.
• Optionally add the FastLED smoke examples to fbuild's example matrix once the core's hardware paths (ADC, PWM, I2C, USB-less serial) firm up — the upstream README flags those as still-pending.

Caveats worth knowing

• The upstream nxplpc PlatformIO platform doesn't bundle an Arduino builder; the recipes in platform.txt (GCC compile/link, OpenOCD upload, vector-checksum tool in tools/lpc8xx_image_check.py) will need to land somewhere on the fbuild/PlatformIO side.
• Upload is CMSIS-DAP via OpenOCD by default; manual ISP fallback is supported.
• Repo status is alpha — compiles and links across all three targets via arduino-cli, but full hardware deployment isn't verified yet.

cc @zackees