remove user-facing English from the library (KeyOrigin::name, hddvd Title)

Library holds ZERO user-facing English (CLAUDE.md). Removed KeyOrigin::name()'s
English prose — apps map the typed enum (freemkv gets key_origin_label); diag
logs the enum's Debug repr. hddvd unnamed-title fallback 'Title N' -> neutral
TITLE_N identifier (UDF volume-label style).

src/diag.rs

@@ -530,7 +530,7 @@ fn dump_aacs(disc: &Disc) {
         a.bus_encryption,
         a.mkb_version,
         a.disc_hash,
-        a.key_source.name(),
+        a.key_source,
         a.vuk.is_some(),
         a.unit_keys.len(),
         a.uk_ro.len(),

src/disc/hddvd.rs

@@ -522,8 +522,10 @@ fn compose_xpl_titles(
             })
             .collect();
         titles.push(DiscTitle {
+            // Language-neutral identifier (no user-facing English in the library):
+            // matches the UDF `TITLE_*` volume-label style. Apps localize display.
             playlist: if t.name.is_empty() {
-                format!("Title {}", t.number)
+                format!("TITLE_{}", t.number)
             } else {
                 t.name.clone()
             },

src/disc/mod.rs

@@ -1440,18 +1440,9 @@ pub enum KeyOrigin {
     ExternalUk,
 }
 
-impl KeyOrigin {
-    pub fn name(&self) -> &'static str {
-        match self {
-            KeyOrigin::DeviceKey => "MKB + device key",
-            KeyOrigin::ProcessingKey => "MKB + processing key",
-            KeyOrigin::KeyDbDerived => "KEYDB (derived)",
-            KeyOrigin::KeyDb => "KEYDB",
-            KeyOrigin::KeyDbUnitKeys => "KEYDB (unit keys)",
-            KeyOrigin::ExternalUk => "external UK",
-        }
-    }
-}
+// No `KeyOrigin::name()`: the library holds ZERO user-facing English (CLAUDE.md).
+// `KeyOrigin` is a typed enum; applications map its variants to display text
+// (see freemkv's `disc_info::key_origin_label`).
 
 // ─── Disc scanning ──────────────────────────────────────────────────────────