fix(pdftract-1psmn): fix mmap test compilation errors

- Add std::sync::Arc import for thread sharing
- Fix lifetime issue in test_sync_multiple_threads using Arc
- Add mut to source in test_empty_file for Read trait

All FileSource tests pass (12/12).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

crates/pdftract-core/src/source/mmap.rs

@@ -177,6 +177,7 @@ mod tests {
     use super::*;
     use std::fs;
     use std::io::Write;
+    use std::sync::Arc;
     use std::thread;
     use tempfile::NamedTempFile;
 
@@ -335,14 +336,14 @@ mod tests {
         let content = b"0123456789";
         temp_file.write_all(content).unwrap();
 
-        let source = MmapSource::open(temp_file.path()).unwrap();
+        let source = Arc::new(MmapSource::open(temp_file.path()).unwrap());
 
         // Spawn multiple threads reading concurrently
         let handles: Vec<_> = (0..4)
             .map(|i| {
-                let source_ref = &source;
+                let source_clone = Arc::clone(&source);
                 thread::spawn(move || {
-                    let bytes = source_ref.read_range(i as u64, 2).unwrap();
+                    let bytes = source_clone.read_range(i as u64, 2).unwrap();
                     bytes.to_vec()
                 })
             })
@@ -434,7 +435,7 @@ mod tests {
     #[test]
     fn test_empty_file() {
         let temp_file = NamedTempFile::new().unwrap();
-        let source = MmapSource::open(temp_file.path()).unwrap();
+        let mut source = MmapSource::open(temp_file.path()).unwrap();
         assert_eq!(source.len(), 0);
 
         let mut buf = [0u8; 10];

notes/pdftract-1psmn.md

@@ -25,7 +25,12 @@ Implemented FileSource as a PdfSource fallback for when memory-mapping is not av
   - `test_large_file`: Handles 100KB file
   - `test_read_mixed_with_seek`: Tests mixed read/seek operations
 
-### 2. crates/pdftract-core/Cargo.toml
+### 2. crates/pdftract-core/src/source/mmap.rs (test fixes)
+- Added `std::sync::Arc` import for thread sharing
+- Fixed lifetime issue in `test_sync_multiple_threads` by using Arc instead of `&source`
+- Added `mut` to source in `test_empty_file` for Read trait compatibility
+
+### 3. crates/pdftract-core/Cargo.toml
 - Added `parking_lot = "0.12"` dependency
 
 ## Acceptance Criteria