docs(readme): document gyro-tilt rework + L3/R3 indicator (EN + CN)

Bring both READMEs up to v0.6.10's user-facing capability:
- Status screen: note the L3/R3 stick-click inverse-flash indicator and
  the ~Nm charge-time token next to the battery.
- Gyro Tilt screen: per-unit factory IMU calibration, dot centres when the
  controller lies flat, and tilt moves the dot in the matching direction.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.CN.md

@@ -264,7 +264,7 @@ scripts/mic_diag.sh bt-trace
 
 #### 1. 状态
 
-连接状态、已配对 DualSense 的蓝牙地址、带条形的电量百分比（`+` 充电中 / `*` 已充满 / `!` 错误）、实时摇杆位置、方向键、面板按键（△ ◯ ✕ □）、L1/R1，以及 L2/R2 模拟扳机填充条。链路指示与电量使用小像素图标。
+连接状态、已配对 DualSense 的蓝牙地址、带条形的电量百分比（`+` 充电中 / `*` 已充满 / `!` 错误）、实时摇杆位置（按下 **L3 / R3** 时，对应的摇杆框会反色闪烁 —— 白底黑点 —— 直到松开）、方向键、面板按键（△ ◯ ✕ □）、L1/R1，以及 L2/R2 模拟扳机填充条。链路指示与电量使用小像素图标。充电时，电池旁会显示到 100% 的预计时间 `~Nm`。
 
 <img src="./assets/oled/oled_sc01.jpg" alt="Status screen on the OLED" width="420">
 
@@ -299,7 +299,7 @@ scripts/mic_diag.sh bt-trace
 
 #### 5. 陀螺仪倾斜
 
-实时 X/Y/Z 加速度计数值，配 40×40 十字准线框。倾斜手柄，点会实时跟随。
+实时 X/Y/Z 加速度计数值，配 40×40 十字准线框。点会实时跟随手柄的倾斜，并在手柄**平放时居中** —— 它使用手柄自带的逐台出厂 IMU 校准（从特性报告 `0x05` 解析），因此每个手柄的静止位置与增益都准确。向左/右、向前/后倾斜时，点会朝相应方向移动。
 
 <img src="./assets/oled/oled_sc05.jpg" alt="Gyro Tilt screen on the OLED" width="420">
 

README.md

@@ -306,7 +306,7 @@ Every screen also paints **`>`** at the top-left edge (next to KEY0) and **`<`**
 
 #### 1. Status
 
-Connection state, paired DualSense BD address, battery % with bar (`+` charging / `*` complete / `!` error), live analog stick positions, D-pad, face buttons (△ ◯ ✕ □), L1/R1, and L2/R2 analog trigger fill bars. The link indicator and battery use small pixel icons.
+Connection state, paired DualSense BD address, battery % with bar (`+` charging / `*` complete / `!` error), live analog stick positions (each stick box flashes inverse — a black dot on a white box — while its **L3 / R3** is clicked in), D-pad, face buttons (△ ◯ ✕ □), L1/R1, and L2/R2 analog trigger fill bars. The link indicator and battery use small pixel icons. While charging, a `~Nm` estimate of the time to 100% appears next to the battery.
 
 <img src="./assets/oled/oled_sc01.jpg" alt="Status screen on the OLED" width="420">
 
@@ -341,7 +341,7 @@ Cycle order: **Off → Feedback → Weapon → Vibration → Bow → Gallop →
 
 #### 5. Gyro Tilt
 
-Live X/Y/Z accelerometer values with a 40×40 crosshair box. Tilt the controller and the dot tracks in real time.
+Live X/Y/Z accelerometer values with a 40×40 crosshair box. The dot tracks the controller's tilt in real time and **sits centered when the controller lies flat** — it's driven by the controller's own per-unit factory IMU calibration (parsed from feature report `0x05`), so the rest position and gain are correct on every controller. Tilting left/right and forward/back moves the dot in the matching direction.
 
 <img src="./assets/oled/oled_sc05.jpg" alt="Gyro Tilt screen on the OLED" width="420">