fix(ci): remove unused Iced image codecs

[Lowband21]

Changes

• Removed image from the workspace iced feature set, leaving advanced, wgpu, thread-pool, wayland-hack, and wayland enabled.
• Regenerated Cargo.lock so image, ravif, rav1e, bitstream-io, core2, and related codec-only transitive crates are no longer in the resolved dependency graph.

Summary

Subwave no longer enables Iced’s unused image feature, so the workspace avoids the AVIF/rav1e codec dependency chain that introduced the yanked/unmaintained core2 advisory while preserving the required WGPU, Wayland, and appsink playback features.

Testing

• cargo deny check advisories — passed.
• cargo audit — passed; it now reports only the existing allowed paste unmaintained warning from wgpu/metal.
• cargo deny check — passed; duplicate-version findings remain warnings.
• cargo tree -i core2 and cargo tree -i image — both reported no matching package in the resolved graph.
• Repository gate passed:

nix develop --impure --expr '
  let
    pkgs = import (builtins.getFlake "nixpkgs") { system = builtins.currentSystem; };
  in pkgs.mkShell {
    nativeBuildInputs = [
      pkgs.cargo
      pkgs.rustc
      pkgs.rustfmt
      pkgs.clippy
      pkgs.pkg-config
      pkgs.cargo-audit
      pkgs.cargo-deny
    ];
    buildInputs = [
      pkgs.glib
      pkgs.gst_all_1.gstreamer
      pkgs.gst_all_1.gst-plugins-base
    ];
  }
' --command bash -lc '
  set -euo pipefail
  export CARGO_INCREMENTAL=0
  cargo fmt --all --check
  cargo deny check
  cargo audit
  cargo clippy --workspace --all-targets --all-features -- -W warnings
  cargo build --workspace --all-features
'

The configured clippy step completed successfully; it still emits pre-existing collapsible_match warnings in subwave_appsink/src/video_player.rs and subwave_wayland/src/pipeline.rs because the gate uses -W warnings.