docs: repo-wide housekeeping — sync README & docs with the code as shipped

Six parallel audits swept the root docs, docs-site, every per-directory
README, and the packaging docs; every claim below was verified against
the source before editing.

- README: Layout gains the six missing crates (pf-client-core,
  pf-presenter, pf-console-ui, pf-ffvk, pf-driver-proto, punktfunk-tray),
  clients/session, api/ and ci/; Linux/Windows client rows reflect the
  shell + Vulkan-session split and the Vulkan Video -> VAAPI/D3D11VA ->
  software decode chains; the "every client over a C ABI" claim is
  corrected (Rust clients link the core directly); tiered stats overlay
  + console shell noted; Apple row mentions AV1.
- CONTRIBUTING: drop the dead CLAUDE.md link (deliberately untracked);
  point at the README's build/invariants sections. SECURITY: 0.9.0.
- host-cli/pairing: --allow-pairing/--require-pairing are no-op legacy
  names — pairing is required by default, --allow-tofu is the real flag;
  document --data-port and --idle-timeout-ms.
- configuration: document PUNKTFUNK_RECOVER_SESSION_CMD (session-crash
  recovery hook), PUNKTFUNK_MDNS, PUNKTFUNK_DATA_PORT.
- virtual-displays/gnome: GNOME per-client scaling shipped (host-
  persisted) — flip the ❌ to ✅ and describe how it works.
- stats: new "Detail levels" section (Off/Compact/Normal/Detailed +
  per-platform cycle gestures); retire the GTK hand-off note.
- clients/install-client/status/roadmap: decode chains, Windows client
  validation narrowed to HDR-only pending, adaptive bitrate, console
  shell, Apple AV1, Windows host vendor list.
- Sub-READMEs: clients/linux rewritten for the re-architecture; session
  Windows decode rung + d3d11va knob; Windows tiered overlay; Android
  minSdk 28; decky file table; host zerocopy/ path; scripts port
  47992 and steamos-host.md; pf-dualsense source path.
- packaging: canary version bases are tag-derived (<next-minor> via
  pf-version.sh/.ps1), codecs-extra not ffmpeg-full, document the
  pinned offline-Skia tarball + SKIA_BINARIES_URL and vulkan-headers.
- Convert 15 dangling design/*.md links to the punktfunk-planning
  prose convention (those docs live in the private planning repo).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

clients/linux/README.md

@@ -1,17 +1,20 @@
 # punktfunk — Linux client
 
 The native **Linux** app for streaming a punktfunk host to your desktop, laptop, or Steam Deck.
-It's a clean GTK4/libadwaita app that finds hosts on your network, pairs with a PIN, and puts a
-low-latency stream on glass at your display's own resolution and refresh rate.
+It's a clean relm4/GTK4/libadwaita **shell** that finds hosts on your network, pairs with a PIN,
+and manages your settings and library — the stream itself runs in the sibling
+**`punktfunk-session`** Vulkan binary ([`clients/session`](../session/README.md)), which the shell
+spawns, putting the picture on glass at your display's own resolution and refresh rate.
 
-Built in Rust, it links the shared **`punktfunk-core`** directly (no C ABI) and speaks the fast
+Built in Rust end to end (no C ABI): the shell shares its plumbing with the session binary through
+**`crates/pf-client-core`**, which links the **`punktfunk-core`** protocol crate and speaks the fast
 **`punktfunk/1`** protocol — QUIC control plane, GF(2¹⁶) FEC + AES-GCM data plane.
 
 ## Features
 
-- **Zero-copy hardware decode** — FFmpeg VAAPI decode → DRM-PRIME dmabuf → `GdkDmabufTexture`
-  (Tier-1 zero-copy on Intel and AMD), with an automatic software-HEVC fallback on NVIDIA or when
-  VAAPI is unavailable.
+- **Zero-copy hardware decode** — the session presenter decodes via **Vulkan Video** on every GPU
+  vendor (including NVIDIA), falling back to FFmpeg VAAPI → DRM-PRIME dmabuf and then software when
+  Vulkan Video is unavailable.
 - **Your display's native mode** — the host builds a virtual output at exactly your WxH@Hz; no
   scaling, no letterboxing. Steady 60 fps at 1080p60, ~6 ms capture→decoded on the LAN.
 - **Audio both ways** — PipeWire playback with a jitter ring, plus mic uplink to the host.
@@ -26,10 +29,10 @@ Built in Rust, it links the shared **`punktfunk-core`** directly (no C ABI) and
   shows its games (Steam + custom) as a poster grid; click one to launch it in the session.
   Fetched from the host's management API over mTLS — paired devices are authorized by their
   certificate, no extra host setup.
-- **Gamepad library launcher** (`--browse host`) — a console-style, controller-driven coverflow of
-  a paired host's library (drifting aurora backdrop, center-focus posters, button hints): A plays
-  the focused title, B quits, L1/R1 jump. Built for the Steam Deck plugin's "Open library" launch;
-  session end returns to the launcher. Arrow keys/Enter/Esc drive it too (no pad needed).
+- **Gamepad library launcher** (`--browse host`) — a console-style, controller-driven library view
+  of a paired host's games, rendered by the session binary's Skia console UI: A plays the focused
+  title, B quits, L1/R1 jump. Built for the Steam Deck plugin's "Open library" launch; session end
+  returns to the launcher. Arrow keys/Enter/Esc drive it too (no pad needed).
 
 ## Get it