fix(windows): clippy/build cleanups the on-glass build surfaced (-D warnings)

Built the host crate (`cargo clippy --features nvenc -D warnings`) and the driver
workspace (`cargo build`) on the RTX box — the project's intended Windows gate,
which `cargo check` (what the goal1/§2.5 work used) never runs. It surfaced lint
issues accumulated across the goal1 / §2.5 / this-session Windows work:

- 9× redundant `as *mut c_void` after `.as_raw_handle()` (already `*mut c_void`):
  idd_push.rs (3, this session), service.rs (3, this session), manager.rs (3,
  pre-existing §2.5 — my OwnedHandle work copied the idiom). Removed the casts +
  the now-unused `use std::ffi::c_void` in idd_push.rs / manager.rs (service still
  uses it).
- `if_same_then_else` in session_plan.rs::resolve_topology (pre-existing goal1
  stage 3): collapsed the two `false` arms into one condition (behavior identical).
- `unused_unsafe` in the driver `pod_init!` macro: it expands at call sites already
  inside an `unsafe` block, where its own `unsafe` is redundant — `#[allow(
  unused_unsafe)]` (needed at the non-unsafe sites, redundant at the nested ones).

After these, BOTH builds are clean on the box — validating the whole session's
blind Windows + driver work compiles + passes clippy on real hardware.

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

packaging/windows/drivers/pf-vdisplay/src/log.rs

@@ -66,6 +66,10 @@ macro_rules! pod_init {
     ($t:ty) => {{
         // SAFETY: $t is a C POD (windows-rs/WDK/IddCx struct); its all-zero bit pattern is a valid
         // zero-initialised value and the caller sets the required .Size/etc fields immediately after.
-        unsafe { ::core::mem::zeroed::<$t>() }
+        // `unused_unsafe`: pod_init! is also expanded at call sites already inside an `unsafe` block
+        // (where this `unsafe` is redundant), but it IS required at the non-unsafe sites — so allow it.
+        #[allow(unused_unsafe)]
+        let zeroed = unsafe { ::core::mem::zeroed::<$t>() };
+        zeroed
     }};
 }