Implement RMK protocol ICD types

[HaoboGu]

Add the complete Interface Control Document (ICD) for the RMK protocol in rmk-types/src/protocol/rmk.rs. This defines the shared type contract between firmware and host for the new postcard-rpc based communication protocol.

[cloudflare-workers-and-pages]

Deploying rmk-rs with    Cloudflare Pages

Latest commit:	43b0a50
Status:	✅  Deploy successful!
Preview URL:	https://92bc1f69.rmk-4a2.pages.dev
Branch Preview URL:	https://feat-postcard-icd.rmk-4a2.pages.dev

View logs

[github-actions]

Size Report

Example	main	PR	Diff	.text	.data	.bss
use_config/nrf52832_ble	354.8 KiB	355.0 KiB	+0.04% ⬆️	+32	0	+128
use_config/nrf52840_ble	405.5 KiB	406.7 KiB	+0.29% ⬆️	+636	0	+608
use_config/nrf52840_ble_split (central)	482.0 KiB	482.8 KiB	+0.15% ⬆️	+624	0	+128
use_config/nrf52840_ble_split (peripheral)	305.2 KiB	305.3 KiB	+0.05% ⬆️	+156	0	+8
use_config/pi_pico_w_ble	645.2 KiB	645.3 KiB	+0.01% ⬆️	-16	0	+128
use_config/rp2040	146.2 KiB	146.2 KiB	+0.02% ⬆️	-88	0	+128
use_config/rp2040_split (central)	157.3 KiB	157.1 KiB	-0.13% ⬇️	-352	0	+128
use_config/rp2040_split (peripheral)	25.9 KiB	26.1 KiB	+0.52% ⬆️	+132	0	+8
use_config/stm32f1	63.4 KiB	63.6 KiB	+0.21% ⬆️	+12	0	+128
use_config/stm32h7	100.5 KiB	100.9 KiB	+0.41% ⬆️	+296	0	+128
use_rust/nrf52832_ble	344.0 KiB	343.8 KiB	-0.04% ⬇️	-296	0	+128
use_rust/nrf52840_ble	402.8 KiB	402.9 KiB	+0.02% ⬆️	-20	0	+128
use_rust/nrf52840_ble_split (central)	492.7 KiB	493.1 KiB	+0.09% ⬆️	+364	0	+128
use_rust/nrf52840_ble_split (peripheral)	302.1 KiB	302.2 KiB	+0.04% ⬆️	+120	0	+8
use_rust/pi_pico_w_ble	645.5 KiB	645.5 KiB	+0.01% ⬆️	-40	0	+128
use_rust/rp2040	146.5 KiB	146.5 KiB	+0.02% ⬆️	-96	0	+128
use_rust/rp2040_split (central)	156.8 KiB	156.7 KiB	-0.05% ⬇️	-216	0	+128
use_rust/rp2040_split (peripheral)	26.5 KiB	26.6 KiB	+0.53% ⬆️	+136	0	+8
use_rust/stm32f1	63.1 KiB	63.5 KiB	+0.55% ⬆️	+228	0	+128
use_rust/stm32h7	120.3 KiB	119.5 KiB	-0.58% ⬇️	-852	0	+128

use_config/nrf52832_ble — 354.8 KiB → 355.0 KiB (+0.04% ⬆️)

use_config/nrf52840_ble — 405.5 KiB → 406.7 KiB (+0.29% ⬆️)

use_config/nrf52840_ble_split (central) — 482.0 KiB → 482.8 KiB (+0.15% ⬆️)

use_config/nrf52840_ble_split (peripheral) — 305.2 KiB → 305.3 KiB (+0.05% ⬆️)

use_config/pi_pico_w_ble — 645.2 KiB → 645.3 KiB (+0.01% ⬆️)

use_config/rp2040 — 146.2 KiB → 146.2 KiB (+0.02% ⬆️)

use_config/rp2040_split (central) — 157.3 KiB → 157.1 KiB (-0.13% ⬇️)

use_config/rp2040_split (peripheral) — 25.9 KiB → 26.1 KiB (+0.52% ⬆️)

use_config/stm32f1 — 63.4 KiB → 63.6 KiB (+0.21% ⬆️)

use_config/stm32h7 — 100.5 KiB → 100.9 KiB (+0.41% ⬆️)

use_rust/nrf52832_ble — 344.0 KiB → 343.8 KiB (-0.04% ⬇️)

use_rust/nrf52840_ble — 402.8 KiB → 402.9 KiB (+0.02% ⬆️)

use_rust/nrf52840_ble_split (central) — 492.7 KiB → 493.1 KiB (+0.09% ⬆️)

use_rust/nrf52840_ble_split (peripheral) — 302.1 KiB → 302.2 KiB (+0.04% ⬆️)

use_rust/pi_pico_w_ble — 645.5 KiB → 645.5 KiB (+0.01% ⬆️)

use_rust/rp2040 — 146.5 KiB → 146.5 KiB (+0.02% ⬆️)

use_rust/rp2040_split (central) — 156.8 KiB → 156.7 KiB (-0.05% ⬇️)

use_rust/rp2040_split (peripheral) — 26.5 KiB → 26.6 KiB (+0.53% ⬆️)

use_rust/stm32f1 — 63.1 KiB → 63.5 KiB (+0.55% ⬆️)

use_rust/stm32h7 — 120.3 KiB → 119.5 KiB (-0.58% ⬇️)