rc2: macOS cross-compile fix + security/recovery hardening

- build.rs: pass target -arch to cc so macos_shim cross-compiles (x86_64-apple-darwin)
- AACS/CSS: unit-aligned decrypting sweep; per-VTS CSS title keys (hard-fail on wrong VTS);
  reject truncated Unit_Key_RO; AACS 2.0 sig-verify skip; CSS bus-auth random nonce
- recovery: gap-filling mapfile load; sweep/copy resume reconciliation; stale-mapfile abort;
  patch wedge/damage-window range reset
- mux: TS continuity + PSI CC desync guards; HEVC numTemporalLayers clamp; MPEG-2 pending
  byte-cap; PS parse_pts marker-bit validation; HdrFormat strict parse; Unknown-variant metadata
- net/keydb: network:// SSRF parity (IPv4-mapped, CGNAT, 0.0.0.0/8, Class-E); bounded keydb
  header read + size cap + error context
- io: durable mapfile fsync; NFS writeback degrade; sync_file_range error capture;
  Windows SCSI u32 transfer guard

build.rs

@@ -8,8 +8,22 @@ fn main() {
         let obj = format!("{out_dir}/macos_shim.o");
         let lib = format!("{out_dir}/libmacos_scsi.a");
 
+        // Build the shim for the TARGET arch, not the host's. A bare `cc` on an
+        // Apple-Silicon CI runner defaults to arm64, so cross-building to
+        // x86_64-apple-darwin would link a host-arch object against x86_64 Rust
+        // code → "Undefined symbols for architecture x86_64". (Still raw `cc`,
+        // not the `cc` crate, which breaks IOKit exclusive access.)
+        let target_arch = std::env::var("CARGO_CFG_TARGET_ARCH").unwrap_or_default();
+        let clang_arch: &str = if target_arch == "aarch64" {
+            "arm64"
+        } else {
+            &target_arch // x86_64 → x86_64
+        };
+
         std::process::Command::new("cc")
             .args([
+                "-arch",
+                clang_arch,
                 "-c",
                 "src/scsi/macos_shim.c",
                 "-o",