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/activities/network/WifiSelectionActivity.cpp

@@ -1,6 +1,7 @@
 #include "WifiSelectionActivity.h"
 
 #include <GfxRenderer.h>
+#include <Logging.h>
 #include <WiFi.h>
 
 #include <map>
@@ -62,7 +63,7 @@ void WifiSelectionActivity::onEnter() {
     if (!lastSsid.empty()) {
       const auto* cred = WIFI_STORE.findCredential(lastSsid);
       if (cred) {
-        Serial.printf("[%lu] [WIFI] Attempting to auto-connect to %s\n", millis(), lastSsid.c_str());
+        LOG_DBG("WIFI", "Attempting to auto-connect to %s", lastSsid.c_str());
         selectedSSID = cred->ssid;
         enteredPassword = cred->password;
         selectedRequiresPassword = !cred->password.empty();
@@ -82,12 +83,12 @@ void WifiSelectionActivity::onEnter() {
 void WifiSelectionActivity::onExit() {
   Activity::onExit();
 
-  Serial.printf("[%lu] [WIFI] [MEM] Free heap at onExit start: %d bytes\n", millis(), ESP.getFreeHeap());
+  LOG_DBG("WIFI] [MEM", "Free heap at onExit start: %d bytes", ESP.getFreeHeap());
 
   // Stop any ongoing WiFi scan
-  Serial.printf("[%lu] [WIFI] Deleting WiFi scan...\n", millis());
+  LOG_DBG("WIFI", "Deleting WiFi scan...");
   WiFi.scanDelete();
-  Serial.printf("[%lu] [WIFI] [MEM] Free heap after scanDelete: %d bytes\n", millis(), ESP.getFreeHeap());
+  LOG_DBG("WIFI] [MEM", "Free heap after scanDelete: %d bytes", ESP.getFreeHeap());
 
   // Note: We do NOT disconnect WiFi here - the parent activity
   // (CrossPointWebServerActivity) manages WiFi connection state. We just clean
@@ -95,25 +96,25 @@ void WifiSelectionActivity::onExit() {
 
   // Acquire mutex before deleting task to ensure task isn't using it
   // This prevents hangs/crashes if the task holds the mutex when deleted
-  Serial.printf("[%lu] [WIFI] Acquiring rendering mutex before task deletion...\n", millis());
+  LOG_DBG("WIFI", "Acquiring rendering mutex before task deletion...");
   xSemaphoreTake(renderingMutex, portMAX_DELAY);
 
   // Delete the display task (we now hold the mutex, so task is blocked if it
   // needs it)
-  Serial.printf("[%lu] [WIFI] Deleting display task...\n", millis());
+  LOG_DBG("WIFI", "Deleting display task...");
   if (displayTaskHandle) {
     vTaskDelete(displayTaskHandle);
     displayTaskHandle = nullptr;
-    Serial.printf("[%lu] [WIFI] Display task deleted\n", millis());
+    LOG_DBG("WIFI", "Display task deleted");
   }
 
   // Now safe to delete the mutex since we own it
-  Serial.printf("[%lu] [WIFI] Deleting mutex...\n", millis());
+  LOG_DBG("WIFI", "Deleting mutex...");
   vSemaphoreDelete(renderingMutex);
   renderingMutex = nullptr;
-  Serial.printf("[%lu] [WIFI] Mutex deleted\n", millis());
+  LOG_DBG("WIFI", "Mutex deleted");
 
-  Serial.printf("[%lu] [WIFI] [MEM] Free heap at onExit end: %d bytes\n", millis(), ESP.getFreeHeap());
+  LOG_DBG("WIFI] [MEM", "Free heap at onExit end: %d bytes", ESP.getFreeHeap());
 }
 
 void WifiSelectionActivity::startWifiScan() {
@@ -211,8 +212,7 @@ void WifiSelectionActivity::selectNetwork(const int index) {
     // Use saved password - connect directly
     enteredPassword = savedCred->password;
     usedSavedPassword = true;
-    Serial.printf("[%lu] [WiFi] Using saved password for %s, length: %zu\n", millis(), selectedSSID.c_str(),
-                  enteredPassword.size());
+    LOG_DBG("WiFi", "Using saved password for %s, length: %zu", selectedSSID.c_str(), enteredPassword.size());
     attemptConnection();
     return;
   }
@@ -290,10 +290,9 @@ void WifiSelectionActivity::checkConnectionStatus() {
       updateRequired = true;
     } else {
       // Using saved password or open network - complete immediately
-      Serial.printf(
-          "[%lu] [WIFI] Connected with saved/open credentials, "
-          "completing immediately\n",
-          millis());
+      LOG_DBG("WIFI",
+              "Connected with saved/open credentials, "
+              "completing immediately");
       onComplete(true);
     }
     return;