tlc: tighten filepos privacy — 0600 permissions + reindent tests

Filepos DB reveals canonical paths of opened files. Use 0600 instead of default umask (0644) so other users cannot read it.

Reindent the HomeGuard struct / scoped_home function inside the #[cfg(test)] mod tests block (functionally correct, just hard to read before).

local/recipes/tui/tlc/source/src/editor/filepos.rs

@@ -1,6 +1,8 @@
 use std::env;
 use std::fs;
 use std::io::Write;
+#[cfg(unix)]
+use std::os::unix::fs::PermissionsExt;
 use std::path::{Path, PathBuf};
 
 /// Saved cursor line/column for a file.
@@ -75,9 +77,12 @@ pub fn save(path: &Path, pos: CursorPos) -> std::io::Result<()> {
         out.push_str(&format!("{}\t{}\t{}\n", k, p.line, p.column));
     }
     let mut f = fs::File::create(&fp)?;
-    f.write_all(out.as_bytes())?;
-    Ok(())
-}
+        let mut perms = f.metadata()?.permissions();
+        perms.set_mode(0o600);
+        f.set_permissions(perms)?;
+        f.write_all(out.as_bytes())?;
+        Ok(())
+    }
 
 fn canonical_key(path: &Path) -> String {
     std::fs::canonicalize(path)
@@ -93,41 +98,48 @@ mod tests {
 
     static HOME_LOCK: Mutex<()> = Mutex::new(());
 
-struct HomeGuard {
-    #[allow(dead_code)]
-    lock: std::sync::MutexGuard<'static, ()>,
-    prev_home: Option<std::ffi::OsString>,
-    prev_xdg: Option<std::ffi::OsString>,
-}
+    struct HomeGuard {
+        #[allow(dead_code)]
+        lock: std::sync::MutexGuard<'static, ()>,
+        prev_home: Option<std::ffi::OsString>,
+        prev_xdg: Option<std::ffi::OsString>,
+    }
 
-impl Drop for HomeGuard {
-    fn drop(&mut self) {
-        match &self.prev_home {
-            Some(v) => std::env::set_var("HOME", v),
-            None => std::env::remove_var("HOME"),
-        }
-        match &self.prev_xdg {
-            Some(v) => std::env::set_var("XDG_CONFIG_HOME", v),
-            None => std::env::remove_var("XDG_CONFIG_HOME"),
+    impl Drop for HomeGuard {
+        fn drop(&mut self) {
+            match &self.prev_home {
+                Some(v) => std::env::set_var("HOME", v),
+                None => std::env::remove_var("HOME"),
+            }
+            match &self.prev_xdg {
+                Some(v) => std::env::set_var("XDG_CONFIG_HOME", v),
+                None => std::env::remove_var("XDG_CONFIG_HOME"),
+            }
         }
     }
-}
 
-fn scoped_home(dir: &std::path::Path) -> HomeGuard {
-    let lock = HOME_LOCK.lock().unwrap_or_else(|e| e.into_inner());
-    let prev_home = std::env::var_os("HOME");
-    let prev_xdg = std::env::var_os("XDG_CONFIG_HOME");
-    std::env::set_var("HOME", dir);
-    std::env::remove_var("XDG_CONFIG_HOME");
-    HomeGuard { lock, prev_home, prev_xdg }
-}
+    fn scoped_home(dir: &std::path::Path) -> HomeGuard {
+        let lock = HOME_LOCK.lock().unwrap_or_else(|e| e.into_inner());
+        let prev_home = std::env::var_os("HOME");
+        let prev_xdg = std::env::var_os("XDG_CONFIG_HOME");
+        std::env::set_var("HOME", dir);
+        std::env::remove_var("XDG_CONFIG_HOME");
+        HomeGuard {
+            lock,
+            prev_home,
+            prev_xdg,
+        }
+    }
 
     #[test]
     fn save_and_load_round_trip() {
         let dir = tempfile::tempdir().unwrap();
         let file = dir.path().join("hello.txt");
         std::fs::write(&file, "hi\n").unwrap();
-        let pos = CursorPos { line: 7, column: 3 };
+        let pos = CursorPos {
+            line: 7,
+            column: 3,
+        };
         let _g = scoped_home(dir.path());
         save(&file, pos).unwrap();
         assert_eq!(load(&file), Some(pos));
@@ -139,9 +151,29 @@ fn scoped_home(dir: &std::path::Path) -> HomeGuard {
         let file = dir.path().join("hello.txt");
         std::fs::write(&file, "hi\n").unwrap();
         let _g = scoped_home(dir.path());
-        save(&file, CursorPos { line: 1, column: 0 }).unwrap();
-        save(&file, CursorPos { line: 9, column: 4 }).unwrap();
-        assert_eq!(load(&file), Some(CursorPos { line: 9, column: 4 }));
+        save(
+            &file,
+            CursorPos {
+                line: 1,
+                column: 0,
+            },
+        )
+        .unwrap();
+        save(
+            &file,
+            CursorPos {
+                line: 9,
+                column: 4,
+            },
+        )
+        .unwrap();
+        assert_eq!(
+            load(&file),
+            Some(CursorPos {
+                line: 9,
+                column: 4
+            })
+        );
     }
 
     #[test]