fix(vdisplay/windows): Windows clippy — per-block SAFETY comments + then_some

The branch's Windows-host code never ran through the fleet Windows clippy (kept off CI); the merge
to main exposed it. Fix the 4 -D warnings failures in cfg(windows) code:
- manager.rs: 3 unsafe blocks (isolate_displays_ccd / force_extend_topology / set_virtual_primary_ccd)
  had one "both arms" SAFETY comment on the `match` line — clippy::undocumented_unsafe_blocks wants it
  immediately before each block. Split into per-block SAFETY comments.
- win_display.rs: `.then(|| …)` on a POD u32 union read → `.then_some(…)` (eager is fine, discarded
  when false) for clippy::unnecessary_lazy_evaluations.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/punktfunk-host/src/windows/win_display.rs

@@ -492,8 +492,10 @@ pub(crate) unsafe fn set_virtual_primary_ccd(keep_target_id: u32) -> Option<Save
         }
         let idx = p.sourceInfo.Anonymous.modeInfoIdx as usize;
         let m = modes.get(idx)?;
+        // `then_some` (eager): `sourceMode.width` is a POD `u32` union read, discarded when the arm is
+        // false — no lazy guard needed. (`then(|| …)` here trips clippy::unnecessary_lazy_evaluations.)
         (m.infoType == DISPLAYCONFIG_MODE_INFO_TYPE_SOURCE)
-            .then(|| m.Anonymous.sourceMode.width as i32)
+            .then_some(m.Anonymous.sourceMode.width as i32)
     })?;
     let others = paths.len().saturating_sub(1);