App icon: scalable SVG for Linux desktops (#12) (#29)

The hicolor theme had only PNGs. The SVG writes out the shapes of
icon-source.deckcraft with the same coordinates, colours and corner radii;
rendered at 1024 px it matches deckcraft-1024.png up to anti-aliasing at
the curved edges. The Linux, Flatpak and FreeBSD packages copy hicolor/
as a whole, so they ship it without further changes.

generated with Claude Code

ATTRIBUTION.md

@@ -21,6 +21,7 @@ deck and UI icons are original work of the DeckCraft contributors (drawn or gene
 | `packaging/macos/dmg/background.svg` | @XusBadia | DeckCraft macOS DMG window background, original work for this repository (2026-10-08), derived from the DeckCraft app icon `assets/app-icon/deckcraft-1024.png` (referenced via `<image>`, not copied); text is outlined Inter / JetBrains Mono glyph paths | MIT OR Apache-2.0 (`LICENSE-MIT`, `LICENSE-APACHE`) | Finder window of the macOS DMG; `packaging/macos/dmg/generate.py` renders it to `background.tiff` |
 | `packaging/macos/dmg/background.tiff` | @XusBadia | Rendered from `packaging/macos/dmg/background.svg` by `packaging/macos/dmg/generate.py` | MIT OR Apache-2.0 (`LICENSE-MIT`, `LICENSE-APACHE`) | 1x + 2x HiDPI TIFF for the macOS DMG window; includes the app icon (see its row) and LittleCMS's built-in sRGB profile ("No copyright, use freely") |
 | `assets/app-icon/deckcraft.icns`, `assets/app-icon/deckcraft.ico` | DeckCraft contributors | generated from the PNGs above by `packaging/icons.sh` (sips/iconutil, `cargo xtask ico`) | MIT OR Apache-2.0 | macOS and Windows app icons |
+| `assets/app-icon/hicolor/scalable/apps/ai.storyteller.deckcraft.svg` | DeckCraft contributors | the shapes of `assets/app-icon/icon-source.deckcraft` written out as SVG (same coordinates, colours and corner radii) | MIT OR Apache-2.0 | Scalable app icon for Linux desktops (hicolor theme) |
 | `assets/app-icon/icon-source.deckcraft` | DeckCraft contributors | made with `deckcraft-cli run` (see git history) | MIT OR Apache-2.0 | Source of the placeholder icon |
 | `docs/images/editor.png`, `docs/images/shape-format.png`, `docs/images/format-pane.png`, `docs/images/slide-sorter.png`, `docs/images/dark-mode.png`, `docs/images/sample-deck.png` | DeckCraft contributors | Screenshots of DeckCraft and slides rendered by `deckcraft-cli` from the built-in sample deck (original content; Inter font, OFL-1.1) | MIT OR Apache-2.0 | README screenshots |
 | `crates/media/tests/fixtures/tone*` (`tone.mp3`, `.m4a`, `.aac`, `.ogg`, `.opus`, `.flac`, `.wma`, `tone-alac.m4a`) | DeckCraft contributors | synthesised 0.5 s 440 Hz sine, encoded by `crates/media/tests/fixtures/make.sh` (ffmpeg as the encoder only) | CC0-1.0 | Audio decoding tests |

assets/app-icon/hicolor/scalable/apps/ai.storyteller.deckcraft.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><rect x="16" y="16" width="480" height="480" rx="111.84" fill="#f26b1d"/><rect x="246" y="330" width="20" height="110" fill="#0b0b0c"/><rect x="176" y="430" width="160" height="18" fill="#0b0b0c"/><rect x="86" y="96" width="340" height="244" rx="14.64" fill="#efe9dc" stroke="#0b0b0c" stroke-width="12"/><rect x="126" y="136" width="170" height="20" fill="#0b0b0c"/><rect x="136" y="236" width="46" height="70" fill="#f26b1d"/><rect x="202" y="196" width="46" height="110" fill="#0b0b0c"/><rect x="268" y="166" width="46" height="140" fill="#f26b1d"/><circle cx="364" cy="178" r="28" fill="#0b0b0c"/></svg>