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/WifiCredentialStore.cpp

@@ -1,7 +1,7 @@
 #include "WifiCredentialStore.h"
 
 #include <HalStorage.h>
-#include <HardwareSerial.h>
+#include <Logging.h>
 #include <Serialization.h>
 
 // Initialize the static instance
@@ -21,7 +21,7 @@ constexpr size_t KEY_LENGTH = sizeof(OBFUSCATION_KEY);
 }  // namespace
 
 void WifiCredentialStore::obfuscate(std::string& data) const {
-  Serial.printf("[%lu] [WCS] Obfuscating/deobfuscating %zu bytes\n", millis(), data.size());
+  LOG_DBG("WCS", "Obfuscating/deobfuscating %zu bytes", data.size());
   for (size_t i = 0; i < data.size(); i++) {
     data[i] ^= OBFUSCATION_KEY[i % KEY_LENGTH];
   }
@@ -45,8 +45,7 @@ bool WifiCredentialStore::saveToFile() const {
   for (const auto& cred : credentials) {
     // Write SSID (plaintext - not sensitive)
     serialization::writeString(file, cred.ssid);
-    Serial.printf("[%lu] [WCS] Saving SSID: %s, password length: %zu\n", millis(), cred.ssid.c_str(),
-                  cred.password.size());
+    LOG_DBG("WCS", "Saving SSID: %s, password length: %zu", cred.ssid.c_str(), cred.password.size());
 
     // Write password (obfuscated)
     std::string obfuscatedPwd = cred.password;
@@ -55,7 +54,7 @@ bool WifiCredentialStore::saveToFile() const {
   }
 
   file.close();
-  Serial.printf("[%lu] [WCS] Saved %zu WiFi credentials to file\n", millis(), credentials.size());
+  LOG_DBG("WCS", "Saved %zu WiFi credentials to file", credentials.size());
   return true;
 }
 
@@ -69,7 +68,7 @@ bool WifiCredentialStore::loadFromFile() {
   uint8_t version;
   serialization::readPod(file, version);
   if (version > WIFI_FILE_VERSION) {
-    Serial.printf("[%lu] [WCS] Unknown file version: %u\n", millis(), version);
+    LOG_DBG("WCS", "Unknown file version: %u", version);
     file.close();
     return false;
   }
@@ -94,16 +93,15 @@ bool WifiCredentialStore::loadFromFile() {
 
     // Read and deobfuscate password
     serialization::readString(file, cred.password);
-    Serial.printf("[%lu] [WCS] Loaded SSID: %s, obfuscated password length: %zu\n", millis(), cred.ssid.c_str(),
-                  cred.password.size());
+    LOG_DBG("WCS", "Loaded SSID: %s, obfuscated password length: %zu", cred.ssid.c_str(), cred.password.size());
     obfuscate(cred.password);  // XOR is symmetric, so same function deobfuscates
-    Serial.printf("[%lu] [WCS] After deobfuscation, password length: %zu\n", millis(), cred.password.size());
+    LOG_DBG("WCS", "After deobfuscation, password length: %zu", cred.password.size());
 
     credentials.push_back(cred);
   }
 
   file.close();
-  Serial.printf("[%lu] [WCS] Loaded %zu WiFi credentials from file\n", millis(), credentials.size());
+  LOG_DBG("WCS", "Loaded %zu WiFi credentials from file", credentials.size());
   return true;
 }
 
@@ -113,19 +111,19 @@ bool WifiCredentialStore::addCredential(const std::string& ssid, const std::stri
                             [&ssid](const WifiCredential& cred) { return cred.ssid == ssid; });
   if (cred != credentials.end()) {
     cred->password = password;
-    Serial.printf("[%lu] [WCS] Updated credentials for: %s\n", millis(), ssid.c_str());
+    LOG_DBG("WCS", "Updated credentials for: %s", ssid.c_str());
     return saveToFile();
   }
 
   // Check if we've reached the limit
   if (credentials.size() >= MAX_NETWORKS) {
-    Serial.printf("[%lu] [WCS] Cannot add more networks, limit of %zu reached\n", millis(), MAX_NETWORKS);
+    LOG_DBG("WCS", "Cannot add more networks, limit of %zu reached", MAX_NETWORKS);
     return false;
   }
 
   // Add new credential
   credentials.push_back({ssid, password});
-  Serial.printf("[%lu] [WCS] Added credentials for: %s\n", millis(), ssid.c_str());
+  LOG_DBG("WCS", "Added credentials for: %s", ssid.c_str());
   return saveToFile();
 }
 
@@ -134,7 +132,7 @@ bool WifiCredentialStore::removeCredential(const std::string& ssid) {
                             [&ssid](const WifiCredential& cred) { return cred.ssid == ssid; });
   if (cred != credentials.end()) {
     credentials.erase(cred);
-    Serial.printf("[%lu] [WCS] Removed credentials for: %s\n", millis(), ssid.c_str());
+    LOG_DBG("WCS", "Removed credentials for: %s", ssid.c_str());
     if (ssid == lastConnectedSsid) {
       clearLastConnectedSsid();
     }
@@ -176,5 +174,5 @@ void WifiCredentialStore::clearAll() {
   credentials.clear();
   lastConnectedSsid.clear();
   saveToFile();
-  Serial.printf("[%lu] [WCS] Cleared all WiFi credentials\n", millis());
+  LOG_DBG("WCS", "Cleared all WiFi credentials");
 }