feat(codec): add TypeError::InvalidValue variant

Add InvalidValue { value: i32 } to TypeError for cases where bytes were
read successfully but the decoded value is not a recognized enum variant.
This replaces the misleading use of UnexpectedEof for invalid enum IDs.

Author: dodoflix

src/snapshots/oxidized_codec__types__tests__invalid_value.snap

@@ -0,0 +1,5 @@
+---
+source: src/types.rs
+expression: "format!(\"{}\", TypeError::InvalidValue { value: 42 })"
+---
+invalid value: 42

src/types.rs

@@ -65,6 +65,13 @@ pub enum TypeError {
     /// Invalid UTF-8 in a string.
     #[error("invalid UTF-8: {0}")]
     InvalidUtf8(#[from] std::string::FromUtf8Error),
+
+    /// Value was successfully read but is not a recognized variant.
+    #[error("invalid value: {value}")]
+    InvalidValue {
+        /// The unrecognized value that was read.
+        value: i32,
+    },
 }
 
 /// Reads a VarInt-length-prefixed UTF-8 string from `buf`.
@@ -397,6 +404,10 @@ mod tests {
             "unexpected_eof",
             format!("{}", TypeError::UnexpectedEof { need: 16, have: 4 })
         );
+        insta::assert_snapshot!(
+            "invalid_value",
+            format!("{}", TypeError::InvalidValue { value: 42 })
+        );
     }
 
     #[test]