feat: D4 DKM colored log prefixes - every driver has its own temper

- log.c: color context (log_set_color / log_color_enable); ANSI only goes to serial, BOOTLOG.TXT buffer stays clean plain text
- kernel_api.c: dkm_log_set_driver() — driver-name FNV-1a hash into an 8-color bright ANSI palette, deterministic per driver
- load sites (dkm_core builtin + boot_modules external) set color around driver_init and clear after
- FUCK [debug] color_log gate (dev=1, release=0)
- QEMU verified: 1150 colored lines, per-driver stable colors (.build_tmp/qemu_serial_d4color.log)

docs/TASKBOARD.md

@@ -25,7 +25,7 @@
 - [ ] D1 DKM 热卸载（引用计数 + 资源回收，循环 100 次不崩）
 - [ ] D2 裸机器码加载器
 - [ ] D3 内核 API 按名导出表（kapi()）
-- [ ] D4 DKM 彩色日志前缀
+- [x] D4 DKM 彩色日志前缀（驱动名 hash → 8 色 ANSI，init 期着色，BOOTLOG 保持纯文本）
 
 ## ⏪ 四期：落款（DRR/PCQ）