fix(cli): add native FreeBSD self-executable path resolution

cbm_detect_self_path had no branch for FreeBSD, falling through to the
generic #else that reads /proc/self/exe. In this environment /proc is a
native FreeBSD procfs mount left empty (only /compat/linux/proc is
populated, for Linux-ABI processes under the compat layer), so the
readlink always failed silently and the function fell back to the
expected install path instead of the actual running binary's path.

This broke install: with no valid self path, the activation transaction
could never confirm what to publish and aborted early with
"activation transaction I/O failed" before attempting any linkat/rename.

Add sysctl(CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1) for FreeBSD,
matching the pattern already used in the test suites, and include
<sys/sysctl.h> guarded by __FreeBSD__.

Signed-off-by: Pedro Ramos <131530838+pr9000@users.noreply.github.com>

Author: PR9000

src/cli/cli.c

@@ -107,6 +107,10 @@ static int cbm_powershell_quote_word(const char *value, char *out, size_t out_si
 #include <stdlib.h>
 #include <string.h>   // strtok_r
 #include <sys/stat.h> // mode_t, S_IXUSR
+#ifdef __FreeBSD__
+#include <sys/types.h>
+#include <sys/sysctl.h>
+#endif
 #include <time.h>
 #include <wchar.h>
 #include <zlib.h> // MAX_WBITS
@@ -8913,6 +8917,13 @@ static bool cbm_detect_self_path(char *buf, size_t buf_sz, const char *home) {
     if (!exact) {
         buf[0] = '\0';
     }
+#elif defined(__FreeBSD__)
+    int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
+    size_t cb = buf_sz;
+    exact = sysctl(mib, 4, buf, &cb, NULL, 0) == 0 && cb > 0;
+    if (!exact) {
+        buf[0] = '\0';
+    }
 #else
     ssize_t sp_len = readlink("/proc/self/exe", buf, buf_sz - SKIP_ONE);
     exact = sp_len > 0 && (size_t)sp_len < buf_sz - SKIP_ONE;