Audit fixes + DVD support foundation (IFO, PS demux, MPEG-2, CSS crack)

Audit fixes (14 critical, 22 warnings):
- UDF: bounds checks on all ICB/FID parsing from disc data
- SCSI Linux: saturating_sub on residual, CDB length guard, buffer size guard
- SCSI macOS: SCSITaskStatus u32 (was u8 — stack corruption)
- AACS: EC mod_inv returns infinity instead of panic, key reduced mod n
- AACS: do_handshake tries all host certs (was returning on first failure)
- H.264: bounds check on SPS < 4 bytes
- ContentReader: error on missing unit key (was zero-fill)
- KEYDB: flat redirect loop (was recursive), 100MB response limit, Windows HOME fallback
- ISO writer: AVDP extent order, partition length, allocation cap
- Network: removed TCP_NODELAY on bulk stream
- MKV: guard on u64::MAX seek
- disc.rs: saturating_sub on extent offset, simplified dead region code
- cargo fmt (610 violations), cargo clippy --fix (55 auto-fixes)

DVD support (new files):
- src/ifo.rs — IFO parser (VIDEO_TS.IFO, VTS_XX_0.IFO, PGC chains, cells, streams) — 13 tests
- src/mux/ps.rs — MPEG-2 Program Stream demuxer (pack headers, PES, private stream 1) — 12 tests
- src/mux/codec/mpeg2.rs — MPEG-2 video parser (sequence headers, I-frame detection) — 15 tests
- src/css/crack.rs — split-attack algorithm (LFSR cipher needs verification — test ignored)

226 tests total (was 186), 1 ignored (CSS crack needs cipher verification).

src/speed.rs

@@ -3,27 +3,37 @@
 /// Common optical drive speeds with KB/s values for SET_CD_SPEED.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
 pub enum DriveSpeed {
-    BD1x, BD2x, BD4x, BD6x, BD8x, BD10x, BD12x,
-    DVD1x, DVD2x, DVD4x, DVD8x, DVD16x,
+    BD1x,
+    BD2x,
+    BD4x,
+    BD6x,
+    BD8x,
+    BD10x,
+    BD12x,
+    DVD1x,
+    DVD2x,
+    DVD4x,
+    DVD8x,
+    DVD16x,
     Max,
 }
 
 impl DriveSpeed {
     pub fn to_kbps(self) -> u16 {
         match self {
-            DriveSpeed::BD1x   => 4_500,
-            DriveSpeed::BD2x   => 9_000,
-            DriveSpeed::BD4x   => 18_000,
-            DriveSpeed::BD6x   => 27_000,
-            DriveSpeed::BD8x   => 36_000,
-            DriveSpeed::BD10x  => 45_000,
-            DriveSpeed::BD12x  => 54_000,
-            DriveSpeed::DVD1x  => 1_385,
-            DriveSpeed::DVD2x  => 2_770,
-            DriveSpeed::DVD4x  => 5_540,
-            DriveSpeed::DVD8x  => 11_080,
+            DriveSpeed::BD1x => 4_500,
+            DriveSpeed::BD2x => 9_000,
+            DriveSpeed::BD4x => 18_000,
+            DriveSpeed::BD6x => 27_000,
+            DriveSpeed::BD8x => 36_000,
+            DriveSpeed::BD10x => 45_000,
+            DriveSpeed::BD12x => 54_000,
+            DriveSpeed::DVD1x => 1_385,
+            DriveSpeed::DVD2x => 2_770,
+            DriveSpeed::DVD4x => 5_540,
+            DriveSpeed::DVD8x => 11_080,
             DriveSpeed::DVD16x => 22_160,
-            DriveSpeed::Max    => 0xFFFF,
+            DriveSpeed::Max => 0xFFFF,
         }
     }
 }