feat: M2 P1.4 — control-stream decryption + input injection (mouse/keyboard live)

A stock Moonlight client can now drive the headless Sway desktop: mouse
movement, buttons, scroll, and keyboard all inject through the streamed
session (verified live end-to-end — typing, clicking, window management).

Control stream (gamestream/control.rs):
- Moonlight encrypts the ENet control stream with AES-128-GCM even though we
  negotiate no media encryption (it detects our Sunshine `state` and turns it
  on). Decrypt per-packet under the /launch `rikey`.
- The exact GCM scheme is auto-detected on the first authenticating packet
  (nonce construction × key byte-order × tag position × AAD) since GCM gives no
  partial credit. Our client uses the legacy 16-byte nonce (`iv[0]=seq&0xff`)
  because we advertise no encryption; the 12-byte SS_ENC_CONTROL_V2 nonce is
  also supported. Key/IV/tag layout cross-checked against Sunshine stream.cpp +
  crypto.cpp and moonlight-common-c ControlStream.c.

Input decode (gamestream/input.rs):
- Decrypted control messages (`[u16 type][u16 len][NV_INPUT packet]`, type
  0x0206) decode into lumen_core::input::InputEvent: relative/abs mouse, buttons,
  vert/horiz scroll, keyboard down/up. Struct layout from moonlight Input.h
  (size BE, magic LE, body BE; keyCode LE masked to the low-byte VK), dispatch
  per Sunshine input.cpp (Gen5+). Unit-tested against real captured bytes.

Injection (inject.rs):
- WlrootsInjector: connects to Sway as a Wayland client and injects via the
  wlroots virtual-pointer + virtual-keyboard protocols (uinput is invisible to a
  compositor running WLR_LIBINPUT_NO_DEVICES=1). Uploads an evdev/US xkb keymap,
  tracks modifier state, and maps Windows VK → Linux evdev (full table).

Deps: aes-gcm, wayland-client, wayland-protocols-{wlr,misc}, xkbcommon (+
libxkbcommon-dev in bootstrap-ubuntu.sh).

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

Cargo.lock

@@ -709,6 +709,12 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "downcast-rs"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "75b325c5dbd37f80359721ad39aca5a29fb04c89279657cffdda8736d0c0b9d2"
+
 [[package]]
 name = "dunce"
 version = "1.0.5"
@@ -1443,6 +1449,7 @@ name = "lumen-host"
 version = "0.0.1"
 dependencies = [
  "aes",
+ "aes-gcm",
  "anyhow",
  "ashpd",
  "axum",
@@ -1463,7 +1470,11 @@ dependencies = [
  "tokio",
  "tracing",
  "tracing-subscriber",
+ "wayland-client",
+ "wayland-protocols-misc",
+ "wayland-protocols-wlr",
  "x509-parser",
+ "xkbcommon",
 ]
 
 [[package]]
@@ -1502,6 +1513,15 @@ version = "2.8.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6b947ae49db0d222b1dbc6b113ce7248a3fc3a6ca21b696717bfc000ba4484d8"
 
+[[package]]
+name = "memmap2"
+version = "0.9.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "714098028fe011992e1c3962653c96b2d578c4b4bce9036e15ff220319b1e0e3"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "memoffset"
 version = "0.9.1"
@@ -1910,6 +1930,15 @@ version = "1.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a1d01941d82fa2ab50be1e79e6714289dd7cde78eba4c074bc5a4374f650dfe0"
 
+[[package]]
+name = "quick-xml"
+version = "0.39.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cdcc8dd4e2f670d309a5f0e83fe36dfdc05af317008fea29144da1a2ac858e5e"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "quinn"
 version = "0.11.9"
@@ -3193,6 +3222,89 @@ dependencies = [
  "semver",
 ]
 
+[[package]]
+name = "wayland-backend"
+version = "0.3.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2857dd20b54e916ec7253b3d6b4d5c4d7d4ca2c33c2e11c6c76a99bd8744755d"
+dependencies = [
+ "cc",
+ "downcast-rs",
+ "rustix",
+ "smallvec",
+ "wayland-sys",
+]
+
+[[package]]
+name = "wayland-client"
+version = "0.31.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "645c7c96bb74690c3189b5c9cb4ca1627062bb23693a4fad9d8c3de958260144"
+dependencies = [
+ "bitflags 2.13.0",
+ "rustix",
+ "wayland-backend",
+ "wayland-scanner",
+]
+
+[[package]]
+name = "wayland-protocols"
+version = "0.32.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "563a85523cade2429938e790815fd7319062103b9f4a2dc806e9b53b95982d8f"
+dependencies = [
+ "bitflags 2.13.0",
+ "wayland-backend",
+ "wayland-client",
+ "wayland-scanner",
+]
+
+[[package]]
+name = "wayland-protocols-misc"
+version = "0.3.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6e9567599ef23e09b8dad6e429e5738d4509dfc46b3b21f32841a304d16b29c8"
+dependencies = [
+ "bitflags 2.13.0",
+ "wayland-backend",
+ "wayland-client",
+ "wayland-protocols",
+ "wayland-scanner",
+]
+
+[[package]]
+name = "wayland-protocols-wlr"
+version = "0.3.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eb04e52f7836d7c7976c78ca0250d61e33873c34156a2a1fc9474828ec268234"
+dependencies = [
+ "bitflags 2.13.0",
+ "wayland-backend",
+ "wayland-client",
+ "wayland-protocols",
+ "wayland-scanner",
+]
+
+[[package]]
+name = "wayland-scanner"
+version = "0.31.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c324a910fd86ebdc364a3e61ec1f11737d3b1d6c273c0239ee8ff4bc0d24b4a"
+dependencies = [
+ "proc-macro2",
+ "quick-xml",
+ "quote",
+]
+
+[[package]]
+name = "wayland-sys"
+version = "0.31.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d8eab23fefc9e41f8e841df4a9c707e8a8c4ed26e944ef69297184de2785e3be"
+dependencies = [
+ "pkg-config",
+]
+
 [[package]]
 name = "web-time"
 version = "1.1.0"
@@ -3597,6 +3709,23 @@ dependencies = [
  "time",
 ]
 
+[[package]]
+name = "xkbcommon"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8d66ca9352cbd4eecbbc40871d8a11b4ac8107cfc528a6e14d7c19c69d0e1ac9"
+dependencies = [
+ "libc",
+ "memmap2",
+ "xkeysym",
+]
+
+[[package]]
+name = "xkeysym"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b9cc00251562a284751c9973bace760d86c0276c471b4be569fe6b068ee97a56"
+
 [[package]]
 name = "yasna"
 version = "0.5.2"