feat: Add central logging pragma (#843)

## Summary

* Definition and use of a central LOG function, that can later be
extended or completely be removed (for public use where debugging
information may not be required) to save flash by suppressing the
-DENABLE_SERIAL_LOG like in the slim branch

* **What changes are included?**

## Additional Context
* By using the central logger the usual:
```
#include <HardwareSerial.h>
...
  Serial.printf("[%lu] [WCS] Obfuscating/deobfuscating %zu bytes\n", millis(), data.size());
```
would then become
```
#include <Logging.h>
...
  LOG_DBG("WCS", "Obfuscating/deobfuscating %zu bytes", data.size());
```
You do have ``LOG_DBG`` for debug messages, ``LOG_ERR`` for error
messages and ``LOG_INF`` for informational messages. Depending on the
verbosity level defined (see below) soe of these message types will be
suppressed/not-compiled.

* The normal compilation (default) will create a firmware.elf file of
42.194.356 bytes, the same code via slim will create 42.024.048 bytes -
170.308 bytes less
* Firmware.bin : 6.469.984 bytes for default, 6.418.672 bytes for slim -
51.312 bytes less


### AI Usage

While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.

Did you use AI tools to help write this code? _NO_

---------

Co-authored-by: Xuan Son Nguyen <son@huggingface.co>

src/main.cpp

@@ -4,6 +4,7 @@
 #include <HalDisplay.h>
 #include <HalGPIO.h>
 #include <HalStorage.h>
+#include <Logging.h>
 #include <SPI.h>
 #include <builtinFonts/all.h>
 
@@ -201,8 +202,8 @@ void enterDeepSleep() {
   enterNewActivity(new SleepActivity(renderer, mappedInputManager));
 
   display.deepSleep();
-  Serial.printf("[%lu] [   ] Power button press calibration value: %lu ms\n", millis(), t2 - t1);
-  Serial.printf("[%lu] [   ] Entering deep sleep.\n", millis());
+  LOG_DBG("MAIN", "Power button press calibration value: %lu ms", t2 - t1);
+  LOG_DBG("MAIN", "Entering deep sleep");
 
   gpio.startDeepSleep();
 }
@@ -255,7 +256,7 @@ void onGoHome() {
 void setupDisplayAndFonts() {
   display.begin();
   renderer.begin();
-  Serial.printf("[%lu] [   ] Display initialized\n", millis());
+  LOG_DBG("MAIN", "Display initialized");
   renderer.insertFont(BOOKERLY_14_FONT_ID, bookerly14FontFamily);
 #ifndef OMIT_FONTS
   renderer.insertFont(BOOKERLY_12_FONT_ID, bookerly12FontFamily);
@@ -274,7 +275,7 @@ void setupDisplayAndFonts() {
   renderer.insertFont(UI_10_FONT_ID, ui10FontFamily);
   renderer.insertFont(UI_12_FONT_ID, ui12FontFamily);
   renderer.insertFont(SMALL_FONT_ID, smallFontFamily);
-  Serial.printf("[%lu] [   ] Fonts setup\n", millis());
+  LOG_DBG("MAIN", "Fonts setup");
 }
 
 void setup() {
@@ -295,7 +296,7 @@ void setup() {
   // SD Card Initialization
   // We need 6 open files concurrently when parsing a new chapter
   if (!Storage.begin()) {
-    Serial.printf("[%lu] [   ] SD card initialization failed\n", millis());
+    LOG_ERR("MAIN", "SD card initialization failed");
     setupDisplayAndFonts();
     exitActivity();
     enterNewActivity(new FullScreenMessageActivity(renderer, mappedInputManager, "SD card error", EpdFontFamily::BOLD));
@@ -310,12 +311,12 @@ void setup() {
   switch (gpio.getWakeupReason()) {
     case HalGPIO::WakeupReason::PowerButton:
       // For normal wakeups, verify power button press duration
-      Serial.printf("[%lu] [   ] Verifying power button press duration\n", millis());
+      LOG_DBG("MAIN", "Verifying power button press duration");
       verifyPowerButtonDuration();
       break;
     case HalGPIO::WakeupReason::AfterUSBPower:
       // If USB power caused a cold boot, go back to sleep
-      Serial.printf("[%lu] [   ] Wakeup reason: After USB Power\n", millis());
+      LOG_DBG("MAIN", "Wakeup reason: After USB Power");
       gpio.startDeepSleep();
       break;
     case HalGPIO::WakeupReason::AfterFlash:
@@ -326,7 +327,7 @@ void setup() {
   }
 
   // First serial output only here to avoid timing inconsistencies for power button press duration verification
-  Serial.printf("[%lu] [   ] Starting CrossPoint version " CROSSPOINT_VERSION "\n", millis());
+  LOG_DBG("MAIN", "Starting CrossPoint version " CROSSPOINT_VERSION);
 
   setupDisplayAndFonts();
 
@@ -364,22 +365,23 @@ void loop() {
   renderer.setFadingFix(SETTINGS.fadingFix);
 
   if (Serial && millis() - lastMemPrint >= 10000) {
-    Serial.printf("[%lu] [MEM] Free: %d bytes, Total: %d bytes, Min Free: %d bytes\n", millis(), ESP.getFreeHeap(),
-                  ESP.getHeapSize(), ESP.getMinFreeHeap());
+    LOG_INF("MEM", "Free: %d bytes, Total: %d bytes, Min Free: %d bytes", ESP.getFreeHeap(), ESP.getHeapSize(),
+            ESP.getMinFreeHeap());
     lastMemPrint = millis();
   }
 
-  // Handle incoming serial commands
-  if (Serial.available() > 0) {
-    String line = Serial.readStringUntil('\n');
+  // Handle incoming serial commands,
+  // nb: we use logSerial from logging to avoid deprecation warnings
+  if (logSerial.available() > 0) {
+    String line = logSerial.readStringUntil('\n');
     if (line.startsWith("CMD:")) {
       String cmd = line.substring(4);
       cmd.trim();
       if (cmd == "SCREENSHOT") {
-        Serial.printf("SCREENSHOT_START:%d\n", HalDisplay::BUFFER_SIZE);
+        logSerial.printf("SCREENSHOT_START:%d\n", HalDisplay::BUFFER_SIZE);
         uint8_t* buf = display.getFrameBuffer();
-        Serial.write(buf, HalDisplay::BUFFER_SIZE);
-        Serial.printf("SCREENSHOT_END\n");
+        logSerial.write(buf, HalDisplay::BUFFER_SIZE);
+        logSerial.printf("SCREENSHOT_END\n");
       }
     }
   }
@@ -392,7 +394,7 @@ void loop() {
 
   const unsigned long sleepTimeoutMs = SETTINGS.getSleepTimeoutMs();
   if (millis() - lastActivityTime >= sleepTimeoutMs) {
-    Serial.printf("[%lu] [SLP] Auto-sleep triggered after %lu ms of inactivity\n", millis(), sleepTimeoutMs);
+    LOG_DBG("SLP", "Auto-sleep triggered after %lu ms of inactivity", sleepTimeoutMs);
     enterDeepSleep();
     // This should never be hit as `enterDeepSleep` calls esp_deep_sleep_start
     return;
@@ -414,8 +416,7 @@ void loop() {
   if (loopDuration > maxLoopDuration) {
     maxLoopDuration = loopDuration;
     if (maxLoopDuration > 50) {
-      Serial.printf("[%lu] [LOOP] New max loop duration: %lu ms (activity: %lu ms)\n", millis(), maxLoopDuration,
-                    activityDuration);
+      LOG_DBG("LOOP", "New max loop duration: %lu ms (activity: %lu ms)", maxLoopDuration, activityDuration);
     }
   }