feat(downloads): redesign download manager

[4gray]

Summary

Redesigns the desktop Download Manager into a polished Queue + Ready to watch MVP based on the approved HTML handoff, while reusing IPTVnator’s existing theme tokens.

What changed

• Keeps one authoritative global download store; source routes now derive scoped views without changing the workspace badge.
• Separates queued/downloading/paused items from failed/canceled attention rows and the completed offline library.
• Adds compact progress rows, status-specific actions, pending guards, honest remove/clear confirmations, search, and All/Movies/Series/In progress filters.
• Groups completed episodes by playlist and series into poster cards with source navigation and a live downloaded-episodes dialog.
• Adds responsive fixed header/filter behavior with one content scroll owner, light/dark theme support, loading skeletons, and compact empty states.
• Adds translations for all 19 locales, architecture documentation, and a user-facing release note.

Validation

• pnpm nx test portal-downloads-feature --runInBand — 162/162
• pnpm nx test services --runInBand — 277/277
• pnpm nx test workspace-shell-feature --runInBand — 124/124
• pnpm nx run electron-backend-e2e:e2e-ci--src/downloads.e2e.ts — 5/5
• pnpm nx run-many -t lint -p portal-downloads-feature services workspace-shell-feature electron-backend-e2e web
• pnpm run typecheck:ci
• pnpm nx build electron-backend
• Prettier, git diff --check, i18n drift, release-note, coverage-policy, and max-lines checks

Electron UI was also exercised through browser automation in light and dark themes at 1280×720, 900×700, and 720×700. This covered single-scroll behavior, narrow-layout overflow, grouped-series dialog accessibility, and long error wrapping. A separate native Computer Use pass was unavailable because the macOS session was locked; the Electron/CDP validation completed successfully.

[greptile-apps]

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Avoid synchronous file probes on every progress refresh

When completed files are stored on a slow or unavailable network volume, this synchronous lstatSync runs once per completed row inside DOWNLOADS_GET_LIST. Active transfers broadcast progress every 500 ms from download-transfer.ts, and each event reloads the global list, so these probes can repeatedly block the Electron main thread and make the UI unresponsive; use asynchronous bounded probing or cache availability outside the progress hot path.

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