Add SP616E serial LED controller support

[MysticCodolic]

Detailed functionality path

The SP616E is a popular, low-cost serial LED controller commonly sold on AliExpress and
used with addressable WS2812B/WS2815 LED strips. It connects via USB (typically
/dev/ttyUSB0 or /dev/ttyACM0) and accepts a simple serial protocol: raw RGB pixel data
followed by a 0xFF terminator byte, at 115200 baud. No header, checksum, or handshake.
User flow:

1. User connects SP616E controller to their HyperHDR host via USB
2. In HyperHDR web UI → LED Hardware → LED Controller, user selects "sp616e" from the
   device type dropdown (under Serial group)
3. User configures:
   • Serial port (e.g. /dev/ttyUSB0, default: ttyACM0)
   • Baud rate (default: 115200)
   • Delay after connect (default: 250ms)
4. HyperHDR sends RGB frames to the controller — each frame is (_ledCount × 3) RGB
   bytes followed by a single 0xFF terminator byte
5. The SP616E drives the connected LED strip in real-time
   Protocol details:

• Frame format: [R0 G0 B0] [R1 G1 B1] ... [Rn Gn Bn] [0xFF]
• No header, no length field, no checksum
• Frame size: (LED count × 3) + 1 bytes
• Default baud rate: 115200
• The 0xFF byte acts as the frame terminator/sync marker
  I have a working implementation ready as a PR that follows the exact same pattern as the
  existing TPM2 and SEDU serial drivers (ProviderSerial base class, auto-registration,
  JSON schema). The implementation is 4 files, +85 lines total.

Justification

1. Affordable hardware access: The SP616E is one of the cheapest USB LED controllers
   available (~$5-10 on AliExpress). Many users already own one from previous AmbiBox
   setups and would benefit from using it with HyperHDR's superior HDR tone mapping
   and performance.
2. Simple protocol, minimal maintenance: The SP616E protocol is trivial (raw RGB +
   terminator) — the entire driver is ~40 lines of code following the established
   ProviderSerial pattern. It requires no special handshake, firmware flashing, or
   complex state management, so maintenance burden is near zero.
3. Migration path from AmbiBox: Many users searching for SP616E + HyperHDR are AmbiBox
   users wanting to upgrade. Native support would eliminate the current answer of
   "not supported, buy different hardware" and provide a smooth migration path.
4. Consistent with existing serial drivers: HyperHDR already supports TPM2, SEDU,
   Adalight, Karate, and other simple serial protocols. The SP616E fits naturally
   into this family with identical architecture and code patterns.
5. No breaking changes: This is purely additive — a new driver class, a JSON schema,
   and a resource file entry. Zero impact on existing drivers or functionality.