fix(brand): crisp taskbar & tray icons (optical-sizing .ico)

[rxm96]

Problem

The taskbar and system-tray icon looked pixelated after the new logo landed (#67).

Root cause (verified)

icons/icon.png is a genuine, crisp 1024×1024 — confirmed by inspecting the bitmap (sharp anti-aliased edges), so the file is fine. The issue is downscaling:

• The only runtime icon source was that single 1024px dark-tile PNG.
• Windows/Electron downscale it to ~16–32px for the taskbar (via electron-builder's generated .ico) and the tray (new Tray()).
• At that size the droplet shrinks, the fine white arrow collapses, and the near-black tile has almost no contrast on the dark Windows taskbar.
• electron-builder can only downscale a single PNG — it can't produce different artwork per size, so it can't fix this.

Fix — optical sizing with real multi-size .ico

Small sizes get dedicated high-contrast artwork; large sizes keep the dark tile (as chosen for the desktop/installer icon).

• icons/icon-small.svg — violet tile + white droplet, tighter padding, for sizes ≤ 48.
• scripts/build-icon.mjs — now rasterizes both SVGs in one offscreen window + one load (a second offscreen data: load fails with ERR_FAILED), crops them apart, high-quality-resizes to each target, and packs Windows .ico files with a small dependency-free ICO packer (PNG payloads):
  • icons/icon.ico — 16/24/32/48 violet + 64/128/256 dark tile
  • icons/tray.ico — 16/24/32 violet
• build.win.icon → icons/icon.ico so the taskbar/installer/exe get native crisp sizes.
• src/main/index.ts — BrowserWindow now sets icon, and the tray uses tray.ico, on Windows (icon.png elsewhere). Previously no window icon was set at all.
• icons/icon.png (1024 dark tile) is unchanged and stays build.icon for macOS/default.

Verification

• ICO files parsed back: correct entry counts/sizes, all valid PNG payloads. Extracted 32px (crisp violet) and 256px (dark tile) and eyeballed them.
• format:check ✓, typecheck ✓ (main process changed), lint 0 errors, npm test 514 ✓, npm run build ✓.
• Regenerate any time with npm run build:icon.

Note: the packaged taskbar/installer icon and the live tray render can only be fully confirmed by a Windows build / running app — local evidence (correct .ico contents + crisp small renders) is strong, final confirmation comes from the next build.

Test plan

• CI verify passes.
• npm run dev → tray + taskbar show the crisp violet icon.
• After a Windows build: installer, desktop shortcut, taskbar, and tray all look crisp.

🤖 Generated with Claude Code