fix(native): replace sandbox-incompatible IPC primitives on macOS

[mujacica]

macOS App Sandbox blocks sem_open(), shm_open(), and fork() in sandboxed apps, causing the native backend to fail during init.

• Replace sem_open/sem_wait with pthread_mutex_t for IPC synchronization
• Replace shm_open with file-backed mmap using $TMPDIR (sandbox-safe)
• Replace fork+exec with posix_spawn using POSIX_SPAWN_CLOEXEC_DEFAULT and explicit fd inheritance via posix_spawn_file_actions_addinherit_np
• Pass shm_fd to daemon via posix_spawn instead of reopening by name
• Add macOS App Sandbox integration tests verifying init, crash capture, minidump generation, and native stacktraces inside a sandboxed .app

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

Autofix Details

Bugbot Autofix prepared a fix for the issue found in the latest run.

• ✅ Fixed: Signal handler extracts first dash instead of last
  • Removed the break statement in the loop so it continues to find the last dash, matching the strrchr behavior in sentry_backend_native.c

Or push these changes by commenting:

@cursor push cc21ef7b97

Preview (cc21ef7b97)

diff --git a/src/backends/native/sentry_crash_handler.c b/src/backends/native/sentry_crash_handler.c
--- a/src/backends/native/sentry_crash_handler.c
+++ b/src/backends/native/sentry_crash_handler.c
@@ -705,7 +705,6 @@
         for (const char *p = shm_id_src; *p; p++) {
             if (*p == '-') {
                 shm_id = p + 1;
-                break;
             }
         }

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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