Replace C Tor with Rust Arti for Tor integration

- Replace C Tor (0.4.8.21) with Rust Arti (1.9.0/arti-client 0.38)
- 70% smaller binary: 21MB xcframework vs 67MB (6.9MB vs 14MB per slice)
- Memory-safe Rust implementation with modern async (tokio)
- Same SOCKS5 proxy interface at 127.0.0.1:39050 for drop-in compatibility
- FFI wrapper (arti-bitchat crate) with C-compatible exports
- Swift TorManager maintains identical public API
- Aggressive size optimization: opt-level=z, lto=fat, panic=abort, strip
- Supports iOS device, iOS simulator (Apple Silicon), and macOS

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

localPackages/Arti/Frameworks/include/arti.h

@@ -0,0 +1,78 @@
+#ifndef ARTI_H
+#define ARTI_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+/**
+ * Start Arti with a SOCKS5 proxy.
+ *
+ * # Arguments
+ * * `data_dir` - Path to data directory for Tor state (C string)
+ * * `socks_port` - Port for SOCKS5 proxy (e.g., 39050)
+ *
+ * # Returns
+ * * 0 on success
+ * * -1 if already running
+ * * -2 if data_dir is invalid
+ * * -3 if runtime initialization failed
+ * * -4 if bootstrap failed
+ */
+int arti_start(const char *data_dir, uint16_t socks_port);
+
+/**
+ * Stop Arti gracefully.
+ *
+ * # Returns
+ * * 0 on success
+ * * -1 if not running
+ */
+int arti_stop(void);
+
+/**
+ * Check if Arti is currently running.
+ *
+ * # Returns
+ * * 1 if running
+ * * 0 if not running
+ */
+int arti_is_running(void);
+
+/**
+ * Get the current bootstrap progress (0-100).
+ */
+int arti_bootstrap_progress(void);
+
+/**
+ * Get the current bootstrap summary string.
+ *
+ * # Arguments
+ * * `buf` - Buffer to write the summary into
+ * * `len` - Length of the buffer
+ *
+ * # Returns
+ * * Number of bytes written (not including null terminator)
+ * * -1 if buffer is null or too small
+ */
+int arti_bootstrap_summary(char *buf, int len);
+
+/**
+ * Signal Arti to go dormant (reduce resource usage).
+ * This is a hint; Arti may not fully support dormant mode yet.
+ *
+ * # Returns
+ * * 0 on success
+ * * -1 if not running
+ */
+int arti_go_dormant(void);
+
+/**
+ * Signal Arti to wake from dormant mode.
+ *
+ * # Returns
+ * * 0 on success
+ * * -1 if not running
+ */
+int arti_wake(void);
+
+#endif  /* ARTI_H */