refactor(windows-host): confine platform code under windows/ + linux/ folders (Goal-1 stage 6)

Move 36 platform-specific files into per-module `windows/` and `linux/` subfolders (and the
shared HID codecs into `inject/proto/`):
  capture/{windows,linux}/  encode/{windows,linux}/  inject/{windows,linux,proto}/
  audio/{windows,linux}/  vdisplay/{windows,linux}/
  src/windows/ (service, wgc_helper, win_adapter, win_display)
  src/linux/  (dmabuf_fence, drm_sync, zerocopy/)

Done with `#[path]`, NOT a module rename: every file moves into its folder while the
`crate::*::*` module names stay FLAT, so all caller paths and every internal `super::`/`crate::`
reference are unchanged — only the parent `mod` decls gained `#[path = "..."]`. This is the
codebase's existing pattern (inject's gamepad_windows) and makes the move byte-identical in
behaviour with ZERO reference churn, far lower risk than collapsing to a single
`crate::capture::windows::` namespace (that deeper rename is an optional follow-on; this delivers
the cfg-sprawl folder confinement the stage is about). Done LAST, after the semantic stages, so
the path churn didn't fight them.

Verified: Linux cargo check + clippy (-D warnings) clean; my mod-decl changes fmt-clean (the 3
remaining fmt diffs are pre-existing local-rustfmt-version skew that moved with their files); all
36 `#[path]` targets exist; no internal `#[path]`/`include!`/file-child-mod in any moved file
(the inline `mod X {` blocks are self-contained). Box build to follow.

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

crates/punktfunk-host/src/audio.rs

@@ -88,6 +88,8 @@ pub fn open_virtual_mic(_channels: u32) -> Result<Box<dyn VirtualMic>> {
 #[cfg(target_os = "linux")]
 mod linux;
 #[cfg(target_os = "windows")]
+#[path = "audio/windows/wasapi_cap.rs"]
 mod wasapi_cap;
 #[cfg(target_os = "windows")]
+#[path = "audio/windows/wasapi_mic.rs"]
 mod wasapi_mic;

crates/punktfunk-host/src/capture.rs

@@ -472,17 +472,25 @@ pub fn capture_virtual_output(
     anyhow::bail!("virtual-output capture requires Linux or Windows")
 }
 
+// Goal-1 stage 6: the Windows backends live under `capture/windows/`, the Linux one under `capture/linux/`
+// (`#[path]` keeps the module names flat, so every `crate::capture::*` path is unchanged).
 #[cfg(target_os = "windows")]
+#[path = "capture/windows/composed_flip.rs"]
 pub mod composed_flip;
 #[cfg(target_os = "windows")]
+#[path = "capture/windows/desktop_watch.rs"]
 pub mod desktop_watch;
 #[cfg(target_os = "windows")]
+#[path = "capture/windows/dxgi.rs"]
 pub mod dxgi;
 #[cfg(target_os = "windows")]
+#[path = "capture/windows/idd_push.rs"]
 pub mod idd_push;
 #[cfg(target_os = "linux")]
 mod linux;
 #[cfg(target_os = "windows")]
+#[path = "capture/windows/wgc.rs"]
 pub mod wgc;
 #[cfg(target_os = "windows")]
+#[path = "capture/windows/wgc_relay.rs"]
 pub mod wgc_relay;

crates/punktfunk-host/src/encode.rs

@@ -531,15 +531,21 @@ pub fn windows_codec_support() -> CodecSupport {
     })
 }
 
+// Goal-1 stage 6: GPU/CPU encoders confined to `encode/windows/` (NVENC, AMF/QSV ffmpeg, software) and
+// `encode/linux/` (NVENC/CUDA + VAAPI); `#[path]` keeps the `crate::encode::*` module names flat.
 #[cfg(all(target_os = "windows", feature = "amf-qsv"))]
+#[path = "encode/windows/ffmpeg_win.rs"]
 mod ffmpeg_win;
 #[cfg(target_os = "linux")]
 mod linux;
 #[cfg(all(target_os = "windows", feature = "nvenc"))]
+#[path = "encode/windows/nvenc.rs"]
 mod nvenc;
 #[cfg(target_os = "windows")]
+#[path = "encode/windows/sw.rs"]
 mod sw;
 #[cfg(target_os = "linux")]
+#[path = "encode/linux/vaapi.rs"]
 mod vaapi;
 
 #[cfg(test)]

crates/punktfunk-host/src/inject.rs

@@ -425,29 +425,39 @@ fn gs_button_to_evdev(b: u32) -> Option<u32> {
     })
 }
 
+// Goal-1 stage 6: Linux UHID/uinput/libei/wlr backends under `inject/linux/`, the Windows UMDF/SendInput
+// backends under `inject/windows/`, and the transport-independent HID codecs under `inject/proto/`;
+// `#[path]` keeps every `crate::inject::*` module name flat.
 #[cfg(target_os = "linux")]
+#[path = "inject/linux/dualsense.rs"]
 pub mod dualsense;
 /// Transport-independent DualSense HID contract, shared by the Linux UHID backend ([`dualsense`])
 /// and the Windows UMDF-driver backend ([`dualsense_windows`]).
 #[cfg(any(target_os = "linux", target_os = "windows"))]
+#[path = "inject/proto/dualsense_proto.rs"]
 pub mod dualsense_proto;
 /// Windows: virtual DualSense via the UMDF minidriver + a shared-memory host channel.
 #[cfg(target_os = "windows")]
+#[path = "inject/windows/dualsense_windows.rs"]
 pub mod dualsense_windows;
 #[cfg(target_os = "linux")]
+#[path = "inject/linux/dualshock4.rs"]
 pub mod dualshock4;
 /// Transport-independent DualShock 4 HID codec used by the Windows UMDF-driver backend
 /// ([`dualshock4_windows`]). (The Linux backend still carries its own copy — see the module FIXME.)
 #[cfg(any(target_os = "linux", target_os = "windows"))]
+#[path = "inject/proto/dualshock4_proto.rs"]
 pub mod dualshock4_proto;
 /// Windows: virtual DualShock 4 via the same UMDF minidriver + shared-memory channel (device-type 1).
 #[cfg(target_os = "windows")]
+#[path = "inject/windows/dualshock4_windows.rs"]
 pub mod dualshock4_windows;
 #[cfg(target_os = "linux")]
+#[path = "inject/linux/gamepad.rs"]
 pub mod gamepad;
 /// Windows: virtual Xbox 360 pads via the in-tree XUSB companion UMDF driver (classic XInput).
 #[cfg(target_os = "windows")]
-#[path = "inject/gamepad_windows.rs"]
+#[path = "inject/windows/gamepad_windows.rs"]
 pub mod gamepad;
 /// Stub — virtual gamepads need Linux uinput or the Windows UMDF drivers; events are dropped elsewhere.
 #[cfg(not(any(target_os = "linux", target_os = "windows")))]
@@ -463,10 +473,13 @@ pub mod gamepad {
     }
 }
 #[cfg(target_os = "linux")]
+#[path = "inject/linux/libei.rs"]
 mod libei;
 #[cfg(target_os = "windows")]
+#[path = "inject/windows/sendinput.rs"]
 mod sendinput;
 #[cfg(target_os = "linux")]
+#[path = "inject/linux/wlr.rs"]
 mod wlr;
 
 #[cfg(test)]

crates/punktfunk-host/src/main.rs

@@ -18,9 +18,13 @@ mod audio;
 mod capture;
 mod config;
 mod discovery;
+// Goal-1 stage 6: top-level platform-only modules live under `src/linux/` and `src/windows/`; `#[path]`
+// keeps the `crate::*` module names flat (every existing path is unchanged).
 #[cfg(target_os = "linux")]
+#[path = "linux/dmabuf_fence.rs"]
 mod dmabuf_fence;
 #[cfg(target_os = "linux")]
+#[path = "linux/drm_sync.rs"]
 mod drm_sync;
 mod encode;
 mod gamestream;
@@ -34,18 +38,23 @@ mod pipeline;
 mod punktfunk1;
 mod pwinit;
 #[cfg(target_os = "windows")]
+#[path = "windows/service.rs"]
 mod service;
 mod session_plan;
 mod session_tuning;
 mod spike;
 mod vdisplay;
 #[cfg(target_os = "windows")]
+#[path = "windows/wgc_helper.rs"]
 mod wgc_helper;
 #[cfg(target_os = "windows")]
+#[path = "windows/win_adapter.rs"]
 mod win_adapter;
 #[cfg(target_os = "windows")]
+#[path = "windows/win_display.rs"]
 mod win_display;
 #[cfg(target_os = "linux")]
+#[path = "linux/zerocopy/mod.rs"]
 mod zerocopy;
 
 use anyhow::{bail, Context, Result};

crates/punktfunk-host/src/vdisplay.rs

@@ -623,17 +623,25 @@ pub fn start_restore_worker() -> std::sync::Arc<()> {
     std::sync::Arc::new(())
 }
 
+// Goal-1 stage 6: per-compositor Linux backends under `vdisplay/linux/`, the Windows IddCx/SudoVDA
+// backends under `vdisplay/windows/`; `#[path]` keeps the `crate::vdisplay::*` module names flat.
 #[cfg(target_os = "linux")]
+#[path = "vdisplay/linux/gamescope.rs"]
 mod gamescope;
 #[cfg(target_os = "linux")]
+#[path = "vdisplay/linux/kwin.rs"]
 mod kwin;
 #[cfg(target_os = "linux")]
+#[path = "vdisplay/linux/mutter.rs"]
 mod mutter;
 #[cfg(target_os = "windows")]
+#[path = "vdisplay/windows/pf_vdisplay.rs"]
 pub(crate) mod pf_vdisplay;
 #[cfg(target_os = "windows")]
+#[path = "vdisplay/windows/sudovda.rs"]
 pub(crate) mod sudovda;
 #[cfg(target_os = "linux")]
+#[path = "vdisplay/linux/wlroots.rs"]
 mod wlroots;
 
 #[cfg(test)]