Audit v3 fixes: all 3 tiers (19 findings)

Tier 1 (compilation + correctness):
- Fix nightly-only is_multiple_of → % 2 != 0 (stable Rust compat)
- Fix parse_sample_rate: check 192 before 96 (was returning wrong rate)
- macOS drive discovery: split unix.rs → linux.rs + macos.rs
- Linux: EACCES returns DevicePermission not DeviceNotFound
- CLI pipe.rs: Ctrl+C signal handler added

Tier 2 (correctness + security):
- MkvStream: reset demuxer after scanning→streaming transition
- Windows SPTI: zero data buffer before ioctl
- AACS cert verification: documented why silently skipped
- KEYDB: HOME + USERPROFILE fallback for Windows
- Library modules: pub(crate) for internal modules
- AACS: explicit re-exports, AES primitives pub(crate)

Tier 3 (performance + polish):
- IsoStream: batch 64-sector reads (was 1 sector at a time)
- DiscStream: buffer swap instead of copy in decrypt_and_buffer
- Vec capacity hints in TS/PS demuxer hot paths
- NetworkStream: TLS warning documented
- Batch rip: per-title progress display
- cargo fmt: 0 violations

319 tests, 0 fmt violations.

src/drive/mod.rs

@@ -6,8 +6,10 @@
 //!   3. `init()` — activate custom firmware. Removes riplock.
 //!   4. `probe_disc()` — probe disc surface. Drive learns optimal speeds.
 
-#[cfg(unix)]
-mod unix;
+#[cfg(target_os = "linux")]
+mod linux;
+#[cfg(target_os = "macos")]
+mod macos;
 #[cfg(windows)]
 mod windows;
 
@@ -209,9 +211,13 @@ impl SectorReader for DriveSession {
 }
 
 pub fn find_drives() -> Vec<(String, DriveId)> {
-    #[cfg(unix)]
+    #[cfg(target_os = "linux")]
     {
-        unix::find_drives()
+        linux::find_drives()
+    }
+    #[cfg(target_os = "macos")]
+    {
+        macos::find_drives()
     }
     #[cfg(windows)]
     {
@@ -224,9 +230,13 @@ pub fn find_drive() -> Option<String> {
 }
 
 pub fn resolve_device(path: &str) -> Result<(String, Option<String>)> {
-    #[cfg(unix)]
+    #[cfg(target_os = "linux")]
     {
-        unix::resolve_device(path)
+        linux::resolve_device(path)
+    }
+    #[cfg(target_os = "macos")]
+    {
+        macos::resolve_device(path)
     }
     #[cfg(windows)]
     {