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/aacs/keydb.rs

@@ -57,7 +57,7 @@ pub struct DiscEntry {
 /// Parse a hex string like "0xABCD..." into bytes.
 pub(crate) fn parse_hex(s: &str) -> Option<Vec<u8>> {
     let s = s.trim().trim_start_matches("0x").trim_start_matches("0X");
-    if !s.len().is_multiple_of(2) {
+    if s.len() % 2 != 0 {
         return None;
     }
     let mut out = Vec::with_capacity(s.len() / 2);