feat(session): console game library — Skia coverflow + SkSL aurora, --browse (phase 4b)

The run loop grows a browse mode: the console library idles between
streams in ONE window (no gamescope handoff), overlay actions launch
sessions via run_browse's callback, session end returns to the library.
The Overlay contract gains menu routing (MenuEvent → haptic pulse),
action draining, and session-phase edges.

pf-console-ui ports the GTK launcher wholesale: the coverflow's springs,
cursor arithmetic and recede/tilt constants move verbatim with their
tests (plus new projection tests — focused-card centering, the inner-
edge-recedes corridor); paint order is draw order (the gtk::Fixed
restack hack is gone); the aurora renders as an SkSL runtime shader at
full rate on every box (the 30 Hz CPU-upscale path and its frozen-on-
Deck fallback are deleted — the generated SkSL is compile-tested);
titles/scenes shape through textlayout (CJK-safe). Poster art streams
in as encoded bytes through the shared model and decodes renderer-side.

The session binary wires --browse host[:port] [--mgmt PORT]: KnownHosts
lookup (unpaired renders the pair-first scene), library + art fetch on
threads, PUNKTFUNK_FAKE_LIBRARY dev hook, and a session_params helper
shared with --connect. The minimal build refuses --browse cleanly.

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

clients/linux-session/Cargo.toml

@@ -17,7 +17,7 @@ default = ["ui"]
 # The Skia console UI (stats OSD, capture HUD, later the gamepad library). Dropping it
 # (`--no-default-features`) is the ~15 MB-smaller power-user build: same streaming,
 # stats on stdout only.
-ui = ["dep:pf-console-ui"]
+ui = ["dep:pf-console-ui", "dep:serde_json"]
 
 # Same Linux gating as the rest of the client stack; elsewhere this is a stub binary.
 [target.'cfg(target_os = "linux")'.dependencies]
@@ -25,6 +25,8 @@ pf-presenter = { path = "../../crates/pf-presenter" }
 pf-console-ui = { path = "../../crates/pf-console-ui", optional = true }
 pf-client-core = { path = "../../crates/pf-client-core" }
 punktfunk-core = { path = "../../crates/punktfunk-core", features = ["quic"] }
+# The fake-library dev hook (`PUNKTFUNK_FAKE_LIBRARY`, browse mode) parses GameEntry JSON.
+serde_json = { version = "1", optional = true }
 anyhow = "1"
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }