style: format the whole tree with cargo fmt (stock defaults, #35)

One-time, mechanical reformat — no functional changes. The tree was not
rustfmt-clean (~1800 hunks across ~100 files); this brings it to stock
`cargo fmt` defaults so a `cargo fmt --check` CI gate can follow.
Behaviour-preserving: 2509 pass / 0 fail / 1 ignored (unchanged baseline),
clippy clean. A .git-blame-ignore-revs entry follows so `git blame`
skips this commit.

src/project/lock.rs

@@ -170,7 +170,10 @@ fn local_hostname() -> String {
 /// Uses `sysinfo` to query the OS process table.
 fn pid_is_alive(pid: u32) -> bool {
     let mut sys = System::new();
-    sys.refresh_processes(sysinfo::ProcessesToUpdate::Some(&[Pid::from_u32(pid)]), true);
+    sys.refresh_processes(
+        sysinfo::ProcessesToUpdate::Some(&[Pid::from_u32(pid)]),
+        true,
+    );
     sys.process(Pid::from_u32(pid)).is_some()
 }
 
@@ -211,7 +214,10 @@ mod tests {
         // The first lock writes our own PID; a second attempt
         // should refuse because the PID is alive on this host.
         let err = Lock::acquire(dir.path()).expect_err("should refuse second acquisition");
-        assert!(matches!(err, LockError::AlreadyHeld { .. }), "unexpected: {err:?}");
+        assert!(
+            matches!(err, LockError::AlreadyHeld { .. }),
+            "unexpected: {err:?}"
+        );
     }
 
     #[test]