fix(windows): resolve PR blockers — nanosleep shim, unsetenv, duplicate typedefs, SOCKET type, el_closesocket

lang/el-compiler/runtime/el_platform_win.h

@@ -48,7 +48,7 @@
 /* ── socket close ─────────────────────────────────────────────────────────── */
 /* Winsock closes sockets with closesocket(), not close() (close() is for file fds). The POSIX
    build defines the same helper as close() so the call sites are identical across platforms. */
-static inline int el_closesocket(int s) { return closesocket((SOCKET)s); }
+static inline int el_closesocket(SOCKET s) { return closesocket(s); }
 
 /* ── winsock init (once, at load) ─────────────────────────────────────────── */
 static void el__win_net_init(void) {
@@ -76,12 +76,35 @@ static inline void* el_win_dlsym(void* handle, const char* name) {
 #define mkdir(path, mode) _mkdir(path)     /* POSIX mkdir(path,mode) → _mkdir(path) */
 #define timegm _mkgmtime                   /* UTC tm → time_t */
 
-/* setenv/unsetenv: not in the Windows CRT; map to _putenv_s. */
+/* setenv/unsetenv: not in the Windows CRT; map to _putenv_s / SetEnvironmentVariable. */
 static inline int setenv(const char* name, const char* value, int overwrite) {
     (void)overwrite;
     return _putenv_s(name, value ? value : "");
 }
-static inline int unsetenv(const char* name) { return _putenv_s(name, ""); }
+static inline int unsetenv(const char* name) {
+    /* _putenv_s(name, "") sets VAR="" rather than removing it.
+     * SetEnvironmentVariableA(name, NULL) truly deletes it from the Win32
+     * env block; then we sync the CRT cache with _putenv("NAME=").       */
+    SetEnvironmentVariableA(name, NULL);
+    size_t len = strlen(name);
+    char *buf = (char*)malloc(len + 2);
+    if (!buf) return -1;
+    memcpy(buf, name, len);
+    buf[len] = '=';
+    buf[len + 1] = '\0';
+    _putenv(buf);
+    free(buf);
+    return 0;
+}
+
+/* nanosleep — not available in MSVC/UCRT; approximate with Sleep(). */
+static inline int el_nanosleep(const struct timespec *req, struct timespec *rem) {
+    (void)rem;
+    DWORD ms = (DWORD)((req->tv_sec * 1000ULL) + (req->tv_nsec / 1000000ULL));
+    Sleep(ms ? ms : 1);
+    return 0;
+}
+#define nanosleep(req, rem) el_nanosleep((req), (rem))
 
 /* localtime_r/gmtime_r: Windows offers localtime_s/gmtime_s with reversed arg order. */
 static inline struct tm* localtime_r(const time_t* t, struct tm* out) {