refactor: reorganize pxl8 into client/src/ module structure

- core/: main entry, types, logging, I/O, RNG
- asset/: ase loader, cart, save, embed
- gfx/: graphics, animation, atlas, fonts, tilemap, transitions
- sfx/: audio
- script/: lua/fennel runtime, REPL
- hal/: platform abstraction (SDL3)
- world/: BSP, world, procedural gen
- math/: math utilities
- game/: GUI, replay
- lua/: Lua API modules

client/src/core/pxl8_log.c

@@ -0,0 +1,113 @@
+#include "pxl8_log.h"
+#include "pxl8_repl.h"
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#define PXL8_LOG_COLOR_ERROR   "\033[38;2;251;73;52m"
+#define PXL8_LOG_COLOR_WARN    "\033[38;2;250;189;47m"
+#define PXL8_LOG_COLOR_INFO    "\033[38;2;184;187;38m"
+#define PXL8_LOG_COLOR_DEBUG   "\033[38;2;131;165;152m"
+#define PXL8_LOG_COLOR_TRACE   "\033[38;2;211;134;155m"
+#define PXL8_LOG_COLOR_RESET   "\033[0m"
+
+static pxl8_log* g_log = NULL;
+
+void pxl8_log_init(pxl8_log* log) {
+    g_log = log;
+    g_log->level = PXL8_LOG_LEVEL_DEBUG;
+
+    const char* env_level = getenv("PXL8_LOG_LEVEL");
+    if (env_level) {
+        if (strcmp(env_level, "trace") == 0) g_log->level = PXL8_LOG_LEVEL_TRACE;
+        else if (strcmp(env_level, "debug") == 0) g_log->level = PXL8_LOG_LEVEL_DEBUG;
+        else if (strcmp(env_level, "info") == 0) g_log->level = PXL8_LOG_LEVEL_INFO;
+        else if (strcmp(env_level, "warn") == 0) g_log->level = PXL8_LOG_LEVEL_WARN;
+        else if (strcmp(env_level, "error") == 0) g_log->level = PXL8_LOG_LEVEL_ERROR;
+    }
+}
+
+void pxl8_log_set_level(pxl8_log_level level) {
+    if (g_log) g_log->level = level;
+}
+
+static void log_timestamp(char* buffer, size_t size) {
+    time_t now = time(NULL);
+    struct tm* tm_info = localtime(&now);
+    strftime(buffer, size, "%H:%M:%S", tm_info);
+}
+
+static void log_output(const char* color, const char* level,
+                       const char* file, int line, const char* fmt, va_list args) {
+    char buffer[4096];
+    char timestamp[16];
+    log_timestamp(timestamp, sizeof(timestamp));
+
+    int pos = 0;
+    if (file) {
+        pos = snprintf(buffer, sizeof(buffer), "%s[%s %s]" PXL8_LOG_COLOR_RESET " %s:%d: ",
+                color, timestamp, level, file, line);
+    } else {
+        pos = snprintf(buffer, sizeof(buffer), "%s[%s %s]" PXL8_LOG_COLOR_RESET " ",
+                color, timestamp, level);
+    }
+
+    if (pos > 0 && pos < (int)sizeof(buffer)) {
+        vsnprintf(buffer + pos, sizeof(buffer) - pos, fmt, args);
+    }
+
+    strncat(buffer, "\n", sizeof(buffer) - strlen(buffer) - 1);
+
+    if (!pxl8_repl_push_log(buffer)) {
+        printf("%s", buffer);
+        fflush(stdout);
+    }
+}
+
+void pxl8_log_write_trace(const char* file, int line, const char* fmt, ...) {
+    if (!g_log || g_log->level > PXL8_LOG_LEVEL_TRACE) return;
+
+    va_list args;
+    va_start(args, fmt);
+    log_output(PXL8_LOG_COLOR_TRACE, "TRACE", file, line, fmt, args);
+    va_end(args);
+}
+
+void pxl8_log_write_debug(const char* file, int line, const char* fmt, ...) {
+    if (!g_log || g_log->level > PXL8_LOG_LEVEL_DEBUG) return;
+
+    va_list args;
+    va_start(args, fmt);
+    log_output(PXL8_LOG_COLOR_DEBUG, "DEBUG", file, line, fmt, args);
+    va_end(args);
+}
+
+void pxl8_log_write_info(const char* fmt, ...) {
+    if (!g_log || g_log->level > PXL8_LOG_LEVEL_INFO) return;
+
+    va_list args;
+    va_start(args, fmt);
+    log_output(PXL8_LOG_COLOR_INFO, "INFO", NULL, 0, fmt, args);
+    va_end(args);
+}
+
+void pxl8_log_write_warn(const char* file, int line, const char* fmt, ...) {
+    if (!g_log || g_log->level > PXL8_LOG_LEVEL_WARN) return;
+
+    va_list args;
+    va_start(args, fmt);
+    log_output(PXL8_LOG_COLOR_WARN, "WARN", file, line, fmt, args);
+    va_end(args);
+}
+
+void pxl8_log_write_error(const char* file, int line, const char* fmt, ...) {
+    if (!g_log || g_log->level > PXL8_LOG_LEVEL_ERROR) return;
+
+    va_list args;
+    va_start(args, fmt);
+    log_output(PXL8_LOG_COLOR_ERROR, "ERROR", file, line, fmt, args);
+    va_end(args);
+}