cross-compile + host FastLED/probe-rs fork (#930 follow-up)

[zackees]

Split-out of #930 (now closed).

Scope

Once the FastLED/probe-rs fork actually flashes an LPC845-BRK against the factory v1.0.7 firmware (blockers under the sibling #930 follow-ups), publish a set of per-target static binaries alongside the LPC-Link2 debugger reflash bundle already at FastLED/framework-arduino-lpc8xx tools/lpc-link2-debugger/.

Cross-compile matrix:

• x86_64-pc-windows-msvc
• aarch64-pc-windows-msvc
• x86_64-apple-darwin
• aarch64-apple-darwin
• x86_64-unknown-linux-gnu
• aarch64-unknown-linux-gnu

Toolchain: cargo zigbuild (same pattern soldr itself uses for its cross-compile lanes). NOT cosmocc — cosmocc is a C-only toolchain and probe-rs' HID/USB stack depends on platform-native APIs (Windows SetupAPI, Linux libusb, macOS IOKit) that don't exist in Cosmopolitan's runtime.

Hosting: add each archive under a dedicated tools/probe-rs/ subdir in FastLED/framework-arduino-lpc8xx (sibling to the existing tools/lpc-link2-debugger/), with SHA256SUMS and a README.md documenting provenance + build reproducibility.

Acceptance

• 6 archives committed to FastLED/framework-arduino-lpc8xx under tools/probe-rs/
• README.md documenting: fork commit, zigbuild version, exact cargo zigbuild command, per-platform SHA256
• Verified: fetching one archive per platform, extracting, running probe-rs list succeeds

Related

• probe-rs on LPC-Link2 CMSIS-DAP v1.0.7: series of upstream quirks to patch through #930 (parent umbrella, closed)
• FastLED/probe-rs fork (the source tree that gets compiled)
• feat(tools): add LPC-Link2 debugger reflash bundle (fbuild#921) framework-arduino-lpc8xx#37 (the sibling tools/lpc-link2-debugger/ bundle that established the hosting pattern)