feat(library): Windows Epic + GOG store providers

EpicProvider reads the launcher's local .item manifests under %ProgramData% (no auth,
launcher need not run) with Playnite's exclusion filter (skip UE_* components +
non-launchable addons + dead install dirs); cover art from the base64 catcache.bin
(public Epic CDN, best-effort). Launch via the com.epicgames.launcher:// URI opened
through explorer.exe — the namespace:catalogItemId:appName triple, with a bare-appName
fallback so a launch is never dropped.

GogProvider enumerates HKLM\SOFTWARE\WOW6432Node\GOG.com\Games (winreg) + each
goggame-<id>.info primary FileTask into a direct-exe spawn (no Galaxy, dodges its
cold-start/anti-cheat). GOG cover art (public api.gog.com) is deferred — it needs an
HTTP fetch + cache off the hot all_games() path — so GOG is title-only for now.

windows_launch_for gains epic/gog arms; both providers wired into all_games() under
cfg(windows). Deps: base64 moved to the cross-platform table (Epic catcache decode +
Lutris art encode both need it); winreg added on the Windows target. Windows unit tests
cover the Epic exclusion filter + URI builder and the GOG spawn + play-task parsing.

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

crates/punktfunk-host/Cargo.toml

@@ -25,6 +25,9 @@ aes-gcm = "0.10"
 cbc = { version = "0.1", features = ["alloc"] }
 rand = "0.8"
 hex = "0.4"
+# Cover-art delivery in the game library: encode Lutris's local JPEGs into `data:` URLs and decode
+# the Epic launcher's base64 `catcache.bin`. Cross-platform (Linux Lutris art + Windows Epic art).
+base64 = "0.22"
 rcgen = { version = "0.13", default-features = false, features = ["aws_lc_rs", "pem"] }
 x509-parser = "0.16"
 axum-server = { version = "0.7", features = ["tls-rustls"] }
@@ -89,9 +92,6 @@ serde_json = "1"
 # SQLite (cc, already needed for ffmpeg/opus) so there's no system libsqlite3 runtime dependency —
 # clean for the deb/rpm/flatpak packaging. Opened read-only/immutable (Lutris may hold it open).
 rusqlite = { version = "0.40", features = ["bundled"] }
-# Inline Lutris's local cover-art JPEGs as `data:` URLs in the library (Lutris has no public CDN
-# keyed by a stable id, unlike Steam/Heroic; a `data:` URL is self-contained — no host-served endpoint).
-base64 = "0.22"
 # Builds/validates the xkb keymap uploaded to the virtual keyboard + tracks modifier state.
 xkbcommon = "0.8"
 # The safe `opus` crate is stereo-only; surround (5.1/7.1) needs the libopus *multistream*
@@ -176,6 +176,9 @@ windows = { version = "0.62", features = [
 # handler / ServiceManager install). Wraps the Win32 service API; the supervision loop itself uses
 # the `windows` crate above.
 windows-service = "0.7"
+# Read the GOG.com install registry (HKLM\SOFTWARE\WOW6432Node\GOG.com\Games) for the GOG store
+# provider — ergonomic + correct-by-construction vs. hand-rolled Reg* FFI for subkey enumeration.
+winreg = "0.56"
 # Software H.264 encoder (GPU-less path + NVENC fallback). The default `source` feature statically
 # compiles OpenH264 (BSD-2) — no system lib, builds on MSVC; nasm on PATH adds the SIMD fast path.
 openh264 = "0.9"