read_file: inline block comments misclassified

Summary

read_file comment header detection mishandles inline block comments:

• let x = 1; /* start does not enter block-comment state, so following * ... lines are not treated as header comments.
• /* comment */ let x = 1; is treated as a header comment even though it has trailing code.

Repro

1. Create a file with:

let x = 1; /* start
 * header line
 */
fn main() {}

1. Call read_file in indentation mode with include_header=true anchored under fn main().

Expected

• Inline /* starts block-comment state for subsequent lines, but the line itself is not a header.
• Single-line /* ... */ with trailing code is not a header comment.

Actual

• Inline /* does not start block-comment state, so header lines are missed.
• /* ... */ code is treated as header.