871ebb31ce
Client-side supersampling/downscaling: the client asks the host to render and encode at chosen-resolution × scale (the host does no scaling) and the presenter rescales the decoded frame to the display. >1 supersamples for sharpness; <1 lightens the host GPU and the link. Default 1.0 = Native, the prior behavior. The geometry lives once in punktfunk_core::render_scale (multiply, preserve aspect ratio, floor to even, clamp to the codec's per-axis ceiling — 4096 for H.264, 8192 otherwise), the Rust twin of the Apple client's RenderScale.swift, consumed by the native session client, the presenter's match-window path, the Windows/Linux settings UIs, Decky, and Android (settings + host connect + unit test). Implemented and platform-verified by the Apple-client-features session (Linux+Android+Apple green there); the punktfunk-core wiring (pub mod render_scale) is restored here after being lost in a working-tree reconciliation. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>