ci(encode): lint and test the feature-gated encode backends

pf-encode's GPU backends are off by default, so almost none of them were under
`-D warnings`:

  - ci.yml lints/tests with default features, which do cover VAAPI, libav-NVENC
    and — via punktfunk-host's `default = ["pyrowave"]` — the PyroWave backends,
    but not `nvenc` or `vulkan-encode`.
  - deb.yml builds those two, but with `cargo build`, where warnings are not errors.

That left enc/linux/nvenc_cuda.rs, enc/linux/vulkan_video.rs and the vendored
vk_av1_encode / vk_valve_rgb bindings — ~8,150 lines carrying ~70 `unsafe` blocks —
never linted anywhere, so the crate's own
`#![deny(clippy::undocumented_unsafe_blocks)]`, its stated unsafe-proof gate, was
never actually enforced on them.

Linux gains a clippy+test leg at the SHIPPED feature set: deb.yml builds
`punktfunk-host/nvenc,punktfunk-host/vulkan-encode` WITHOUT
`--no-default-features`, so the .deb carries pyrowave too and that combination is
what deserves the lint. GPU-free — the hardware tests are `#[ignore]`d and
NVENC/CUDA dlopen their entry points, so the test binary links with no driver.

Windows gains a separate `-p pf-encode --all-targets` lint. The existing lint is
`-p punktfunk-host`, which never builds pf-encode's test targets — the blind spot
that let the Linux twin's tests rot. It must be clippy rather than `cargo test`:
on MSVC nvidia-video-codec-sdk link-imports NvEncodeAPICreateInstance /
NvEncodeAPIGetMaxSupportedVersion, so a test binary cannot link without the
driver's import lib. clippy type-checks without linking; ci.yml runs the tests.

`--all-targets` is load-bearing, not decoration: without it the feature-gated
`#[cfg(test)]` modules are never compiled at all.

Also widens windows-host.yml's paths filter, which listed `crates/pf-encode/**`
but none of the crates it compiles against (pf-frame, pf-gpu, pf-zerocopy,
pf-host-config, pf-capture, ...), so a change reaching the Windows host through
one of those triggered no Windows build.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.gitea/workflows/windows-host.yml

@@ -50,6 +50,23 @@ on:
       # builds — without these, encoder changes only reached this workflow via Cargo.lock luck.
       - 'crates/pf-encode/**'
       - 'crates/libvpl-sys/**'
+      # …and the rest of the W6 subsystem crates this build compiles. pf-encode was listed while
+      # the crates it speaks (pf-frame's CapturedFrame/PixelFormat/dxgi vocabulary, pf-gpu's
+      # adapter selection, pf-zerocopy, pf-host-config) were not, so a change that broke the
+      # Windows host through one of THEM reached main with no Windows build at all — the same
+      # Cargo.lock-luck gap the two lines above were added to close.
+      - 'crates/pf-frame/**'
+      - 'crates/pf-gpu/**'
+      - 'crates/pf-zerocopy/**'
+      - 'crates/pf-host-config/**'
+      - 'crates/pf-capture/**'
+      - 'crates/pf-win-display/**'
+      - 'crates/pf-vdisplay/**'
+      - 'crates/pf-inject/**'
+      - 'crates/pf-paths/**'
+      - 'crates/pf-driver-proto/**'
+      - 'crates/pf-clipboard/**'
+      - 'crates/pyrowave-sys/**'
       - 'packaging/windows/**'
       - 'scripts/windows/**'
       - 'web/**'
@@ -154,8 +171,23 @@ jobs:
         # build minutes earlier). Linting in release reuses those native build-script artifacts (no
         # openh264 rebuild), and keeps everything in one C:\t\release tree. Same reason
         # pf-vkhdr-layer's clippy below runs --release.
+        #
+        # pf-encode is linted SEPARATELY with --all-targets so its Windows `#[cfg(test)]` modules
+        # are type-checked — the AMF C-ABI layout assertions (`variant_layout_matches_c` and
+        # friends, which are the only guard on a hand-mirrored vtable ABI), the QSV tests, and the
+        # PyroWave-Windows smoke test. The host lint above cannot cover them: `-p punktfunk-host`
+        # only builds pf-encode as a dependency, so its test targets are never compiled, and that
+        # blind spot is what let the Linux twin's tests rot to the wrong arity unnoticed.
+        # NOTE: clippy (a check, no link step) is deliberately the vehicle here — `cargo test`
+        # with `nvenc` cannot LINK on MSVC: nvidia-video-codec-sdk link-imports
+        # NvEncodeAPICreateInstance / NvEncodeAPIGetMaxSupportedVersion, which resolve only against
+        # the driver's import lib. (On Linux the same crate dlopens them, so ci.yml can and does
+        # run the tests there.) Running them here would need an `--features amf-qsv,qsv` build
+        # without `nvenc`, i.e. a third full dep tree on a runner that already trips C1069 — not
+        # worth it while ci.yml executes the same tests.
         run: |
           cargo clippy --release -p punktfunk-host --features nvenc,amf-qsv,qsv -- -D warnings; if ($LASTEXITCODE) { throw "host clippy" }
+          cargo clippy --release -p pf-encode --all-targets --features nvenc,amf-qsv,qsv -- -D warnings; if ($LASTEXITCODE) { throw "pf-encode clippy" }
           cargo clippy --release -p punktfunk-tray -- -D warnings; if ($LASTEXITCODE) { throw "tray clippy" }
 
       - name: Build + lint the HDR Vulkan layer (pf-vkhdr-layer)