Load covers through the asset protocol instead of base64 over IPC

[firsttris]

What / why

Covers over the asset protocol. get_game_cover and get_game_icon used to read the whole cached image and send it as a base64 data: URL over IPC, which is about a third larger plus encoding and decoding on both sides. GameCard and GameListRow then refetched it on every games refresh, because their $effect depended on the whole game object, and each refresh creates a new object.

• Both commands now return the path of the cache file. The frontend turns it into an asset:// URL with convertFileSrc (src/lib/stores/steamgriddb.ts).
• tauri.conf.json turns on app.security.assetProtocol with its scope limited to $APPDATA/artwork/*, the cover/icon cache dir, top level only. This needs the protocol-asset feature on tauri, which adds a single new crate, http-range, to Cargo.lock. I edited the lock by hand so the rest of it stays untouched; --locked accepts it.
• The URL carries ?v=<grid id>, so a newly chosen image is not shadowed by the webview cache. The asset protocol ignores the query.
• The cards now depend only on id, cover_url and cover_grid_id (via $derived) and drop results from outdated requests.
• Cover <img>s get loading="lazy" and decoding="async".
• Removed image_data_url and image_mime along with their tests. The base64 crate stays because icons.rs uses it.

Static cleanup. Removed the unused template files static/svelte.svg, tauri.svg and vite.svg. A grep found no references outside .git.

Measured

• IPC payload per cover: before, the full image as base64 (about 1.33× the file size, so tens to hundreds of KB per grid image). After, only the path (about 100 B). The webview reads the file itself and caches it.
• Refetches: before, one get_game_cover call per card on every refreshGames(). After, a call only when the id, cover URL or grid id changes.

How tested

• bun run check: 0 errors, 0 warnings.
• bun run test and bun run build pass.
• cargo test --locked: 128 passed. A cargo build --locked (dev profile) has no warnings, and tauri-build accepts the feature and config combination.
• Not run here: cargo build --release (too little disk space in the sandbox; CI covers it), and a manual check in the running app since there's no display. Worth a quick look that covers show up in the grid and list views and that switching a cover updates the card.

🤖 Generated with Claude Code

https://claude.ai/code/session_019UYcbUoJWjGexas7Tjz9Ko

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