fix(gui): fit keyboard image and render glow live

[davidbudnick]

Fixes #272

Context

• keyboard image rendered too wide on the detail view, now contain-fit to the panel and centred
• works for any keyboard, not just the g513 (label-less devices drop the side gutter)
• lighting glow is painted live from the baked run-mask, scaled, behind the keys — no pre-rendered png
• sweeps the old glow-*.png cache files on startup

Testing

• fmt + clippy --workspace --all-targets -D warnings clean
• cargo test --workspace passes (new glow-decode + cache-cleanup tests)
• ran the gui on a g513: keyboard fits, rgb glows behind the keys, stale pngs removed from the cache

Demo

Screen.Recording.2026-06-17.at.9.26.20.AM.mov

[greptile-apps]

Greptile Summary

This PR replaces the old async glow-PNG pipeline (background thread → file cache → stat-on-render) with live canvas rendering from a pre-decoded GlowGeometry struct, and fixes keyboard image overflow in the detail view by adding a max_w clamp to asset_dimensions_for_png.

• Live glow rendering: GlowGeometry is decoded once at asset resolve time from the depot's baked RLE mask and stored as an Arc. On each render, glow_canvas paints normalized segments as scaled quads behind the device image, using a contain-fit that mirrors the device image's ObjectFit::Contain — no per-colour textures and no filesystem reads on the render thread.
• Keyboard image sizing: asset_dimensions_for_png now takes a max_w argument; keyboards that would exceed the panel width are scaled down proportionally. asset_has_button_labels lets keyboards drop the side-label gutter, giving them the full panel width.
• Cleanup: Legacy glow-*.png files are swept from the user cache off-thread on startup, and AppState's glow-attempted/glow-ready HashSet fields are removed entirely.

Confidence Score: 5/5

Safe to merge — changes are additive rendering improvements with no new failure modes on the critical path.

The glow pipeline simplification removes async state machinery and replaces it with a synchronous, pure-function canvas pass derived from pre-decoded geometry. The keyboard overflow fix is a straightforward width clamp. No filesystem writes on the render thread, no new global state, and the cleanup sweep is best-effort off-thread. All three new test functions exercise the new code paths directly, and existing tests are unaffected.

No files require special attention.

Important Files Changed

Filename	Overview
crates/openlogi-gui/src/asset/glow.rs	Replaces the PNG-render pipeline with GlowGeometry (normalized segments + aspect ratio) decoded from the RLE mask once at resolve time. Row-boundary splitting and dimension validation are correct; three new unit tests cover normal extraction, cross-row splits, and invalid run totals.
crates/openlogi-gui/src/app.rs	Removes ensure_glow/GlowJob machinery; adds keyboard_glow (state lookup → color conversion) and glow_canvas (contain-fit quad painter). Rendering order in device_card correctly places the canvas before device_image so it paints behind the keys.
crates/openlogi-gui/src/asset/mod.rs	Adds glow field to ResolvedAsset (decoded once, Arc-shared) and cleanup_legacy_glow_pngs / cleanup_glow_pngs_in. Test correctly captures booleans before cleanup so assertions don't prevent cleanup on failure.
crates/openlogi-gui/src/mouse_model/geometry.rs	asset_dimensions_for_png gains a max_w clamp (fixes keyboard overflow); asset_has_button_labels added to drive gutter presence. The png_height==0 early-return still returns MOUSE_MODEL_SIZE without applying max_w, but that path is only reachable for the mouse fallback (not keyboards).
crates/openlogi-gui/src/mouse_model/view.rs	Layout updated to conditionally drop the side-label gutter for keyboards (has_labels), capping image width at MODEL_CONTENT_MAX_W. Glow is fetched from state and passed through to breathing_art for detail-view rendering behind the device image.
crates/openlogi-gui/src/state.rs	Removes glow_attempted and glow_ready HashSet fields and their associated methods — clean deletion with no remaining references.
crates/openlogi-gui/src/main.rs	Calls cleanup_legacy_glow_pngs via std::thread::spawn at startup — no-arg fn pointer form is valid and keeps the sweep off the render thread.

_{Reviews (2): Last reviewed commit: "style(gui): rustfmt the glow cleanup tes..." | Re-trigger Greptile}