refactor(log): migra core/resources i core/system a Log::

- resource_pack.cpp i resource_cache.cpp: tots els std::cerr passen a
  Log::error.
- director.cpp: std::cout/cerr/fprintf → Log::info / error / critical
  segons severitat.
- printWithDots (utils.cpp): ara és un wrapper sobre Log::info que
  manté l'amplada total (~50 chars) reproduint l'alineació de punts.
  Els callers pasen el tag sense " : " (ja l'afegeix el logger).
- pack_resources: afegit log.cpp i SDL3 al target perquè
  resource_pack.cpp ara depèn de Log::.

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

source/core/resources/resource_pack.cpp

@@ -4,7 +4,8 @@
 #include <array>
 #include <filesystem>
 #include <fstream>
-#include <iostream>
+
+#include "utils/log.hpp"
 
 namespace Resource {
 
@@ -40,14 +41,14 @@ namespace Resource {
         std::array<char, 4> header{};
         file.read(header.data(), 4);
         if (std::string(header.data(), 4) != MAGIC) {
-            std::cerr << "Resource::Pack: invalid pack file format (bad magic): " << pack_file << '\n';
+            Log::error("Resource::Pack", "invalid pack file format (bad magic): {}", pack_file);
             return false;
         }
 
         std::uint32_t version = 0;
         file.read(reinterpret_cast<char*>(&version), sizeof(version));
         if (version != VERSION) {
-            std::cerr << "Resource::Pack: unsupported pack version: " << version << '\n';
+            Log::error("Resource::Pack", "unsupported pack version: {}", version);
             return false;
         }
 
@@ -86,7 +87,7 @@ namespace Resource {
     auto Pack::savePack(const std::string& pack_file) const -> bool {
         std::ofstream file(pack_file, std::ios::binary);
         if (!file) {
-            std::cerr << "Resource::Pack: could not create pack file: " << pack_file << '\n';
+            Log::error("Resource::Pack", "could not create pack file: {}", pack_file);
             return false;
         }
 
@@ -120,7 +121,7 @@ namespace Resource {
     auto Pack::addFile(const std::string& filename, const std::string& filepath) -> bool {
         std::ifstream file(filepath, std::ios::binary | std::ios::ate);
         if (!file) {
-            std::cerr << "Resource::Pack: could not open file: " << filepath << '\n';
+            Log::error("Resource::Pack", "could not open file: {}", filepath);
             return false;
         }
 
@@ -129,7 +130,7 @@ namespace Resource {
 
         std::vector<std::uint8_t> file_data(file_size);
         if (!file.read(reinterpret_cast<char*>(file_data.data()), file_size)) {
-            std::cerr << "Resource::Pack: could not read file: " << filepath << '\n';
+            Log::error("Resource::Pack", "could not read file: {}", filepath);
             return false;
         }
 
@@ -146,7 +147,7 @@ namespace Resource {
 
     auto Pack::addDirectory(const std::string& directory) -> bool {
         if (!std::filesystem::exists(directory)) {
-            std::cerr << "Resource::Pack: directory does not exist: " << directory << '\n';
+            Log::error("Resource::Pack", "directory does not exist: {}", directory);
             return false;
         }
 
@@ -169,7 +170,7 @@ namespace Resource {
 
         const PackEntry& entry = it->second;
         if (entry.offset + entry.size > data_.size()) {
-            std::cerr << "Resource::Pack: invalid resource data: " << filename << '\n';
+            Log::error("Resource::Pack", "invalid resource data: {}", filename);
             return {};
         }
 
@@ -179,7 +180,7 @@ namespace Resource {
 
         std::uint32_t checksum = calculateChecksum(result);
         if (checksum != entry.checksum) {
-            std::cerr << "Resource::Pack: checksum mismatch for: " << filename << '\n';
+            Log::error("Resource::Pack", "checksum mismatch for: {}", filename);
         }
         return result;
     }