[docs][clock_time] Update clock time subsystem documentation

- Update device driver index to use correct page reference
- Clarify upper layer responsibilities in architecture overview
- Update README to describe POSIX/libc, Soft RTC, and device driver usage
- Refine architecture diagram with improved layout and color scheme
- Remove obsolete clock_timer.md file

Author: BernardXiong

documentation/6.components/device-driver/INDEX.md

@@ -8,7 +8,7 @@
 - @subpage page_device_spi
 - @subpage page_device_pwm
 - @subpage page_device_rtc
-- @subpage page_device_clock_timer
+- @subpage page_device_clock_time
 - @subpage page_device_watchdog
 - @subpage page_device_wlan
 - @subpage page_device_sensor

documentation/6.components/device-driver/clock_time/README.md

@@ -13,9 +13,11 @@ hardware counters and timers while the kernel and libc see consistent behavior.
 
 ## Layering and Responsibilities
 
-- Upper layers: kernel services (timeouts, delays), POSIX/libc time APIs
-  (clock_gettime, nanosleep), and RTC/soft-RTC consume the monotonic time base
-  and timer events exposed by clock_time.
+- Upper layers:
+  - POSIX/libc time APIs (clock_gettime, nanosleep) use boottime and hrtimer APIs.
+  - Soft RTC uses boottime as its monotonic time base for timekeeping.
+  - Device drivers (input event timestamps, vDSO, PIC statistics) use boottime
+    for timestamping.
 - clock_time subsystem: core APIs, clock source/event devices, the hrtimer
   scheduler, boottime helpers, and the clock_timer adapter.
 - Lower layers: BSP drivers provide hardware counters and timers, which are

documentation/6.components/device-driver/clock_time/README_zh.md

@@ -10,8 +10,10 @@ clock_time 子系统为 RT-Thread 提供统一的高精度时间基准与事件
 
 ## 分层关系与职责
 
-- 上层：内核超时/延时、POSIX/libc 时间接口（clock_gettime、nanosleep），
-  以及 RTC/软 RTC，直接使用 clock_time 提供的时间与事件能力。
+- 上层：
+  - POSIX/libc 时间接口（clock_gettime、nanosleep）使用 boottime 和 hrtimer API。
+  - 软 RTC 使用 boottime 作为单调时间基准进行计时。
+  - 设备驱动（输入事件时间戳、vDSO、中断控制器统计）使用 boottime 获取时间戳。
 - clock_time 子系统：核心 API、时钟源/事件设备、高精度定时器调度器、
   boottime 辅助函数、clock_timer 适配层。
 - 下层：BSP 驱动提供硬件计数器与定时器，并封装为 clock_time 设备或