feat(wio-tracker-l1): add settings screen and companion radio improvements

Settings screen (UI_HAS_JOYSTICK_UPDOWN build variant):
- Display brightness (5 levels, contrast curve tuned for SH1106 non-linearity)
- Buzzer on/off (respected at startup, no more forced unmute)
- TX power (2–22 dBm)
- Auto-off delay (5s / 15s / 30s / 60s / never)
- GPS update interval (off / 30s / 1min / 5min / 15min / 30min)
- Timezone offset (UTC-12..+14) for clock screen
- Low battery auto-shutdown threshold (off / 3.0–3.5V, default 3.4V)
- Battery display mode (icon / % / voltage)

Battery:
- EMA filter (alpha=0.2) on ADC readings to smooth voltage spikes from uneven load
- Battery % calculated using low_batt_mv as 0% anchor
- Mute icon repositions dynamically based on battery display width

Clock screen on HomeScreen showing time/date with timezone support.

Build:
- _settings variants added for USB and BLE companion radio builds
- Automatic UF2 generation on every build via create-uf2.py post-script
- UI_HAS_JOYSTICK_UPDOWN flag guards joystick_up/down to avoid breaking other boards

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/helpers/ui/DisplayDriver.h

@@ -96,5 +96,6 @@ public:
     print(temp_str);
   }
   
+  virtual void setBrightness(uint8_t level) { }  // level 0-4 (min to max), no-op default
   virtual void endFrame() = 0;
 };

src/helpers/ui/SH1106Display.cpp

@@ -85,6 +85,15 @@ uint16_t SH1106Display::getTextWidth(const char *str)
   return w;
 }
 
+void SH1106Display::setBrightness(uint8_t level)
+{
+  // OLED contrast is highly non-linear: most perceptible change is in the low range.
+  // Values are tuned so each step looks visually distinct.
+  static const uint8_t contrast_values[] = { 8, 30, 80, 160, 255 };
+  uint8_t contrast = contrast_values[level < 5 ? level : 4];
+  display.setContrast(contrast);
+}
+
 void SH1106Display::endFrame()
 {
   display.display();

src/helpers/ui/SH1106Display.h

@@ -39,5 +39,6 @@ public:
   void drawRect(int x, int y, int w, int h) override;
   void drawXbm(int x, int y, const uint8_t *bits, int w, int h) override;
   uint16_t getTextWidth(const char *str) override;
+  void setBrightness(uint8_t level) override;
   void endFrame() override;
 };

src/helpers/ui/buzzer.cpp

@@ -9,7 +9,6 @@ void genericBuzzer::begin() {
       digitalWrite(PIN_BUZZER_EN, HIGH);
     #endif
 
-    quiet(false);
     pinMode(PIN_BUZZER, OUTPUT);
     digitalWrite(PIN_BUZZER, LOW); // need to pull low by default to avoid extreme power draw
     startup();