In-app listening stats, streaks, monthly recap popup, and per-song cloud sync

[LargeModGames]

What's new

• Stats screen (Library sidebar entry): period tabs (7d / 30d / month / year / all), top tracks/artists/albums, last-10-days bars, and playable top tracks (Enter starts playback for Spotify tracks). Cycle periods with [ / ].
• Listening streaks: current/longest streak and time listened today, shown on the Home screen and in the Stats summary. Maintained incrementally by the history collector, so no file re-reads per track.
• Monthly recap popup: when a recap is due (30 days since the last one), a prompt offers to open the generated share page. Dismissable with Esc ("later") or d (never again, persisted; re-enable in Settings). Never steals focus from an input field.
• Offline share card: the recap HTML page renders a downloadable 440x660 share card with a pure canvas renderer (no external JS), toggleable between the requested period and All Time.
• Per-song cloud sync: finished listens now push to spotatui.com as each song completes instead of only at open/close, so long sessions no longer stall the exit sync. An in-flight guard prevents overlapping syncs from double-sending; the exit sync remains as the backstop for the final track.

Implementation notes

• Recap generation runs through IoEvent::GenerateRecap on the network layer with spawn_blocking; the UI thread never blocks on export.
• The RecapPrompt popup is wired into all modal mechanisms (input-mode gate, escape handling, mouse exclusion) like the other prompts.
• Streaks are computed from per-day totals kept in memory by the collector; the listens file is parsed once at startup instead of after every track.

Testing

• cargo fmt, cargo clippy --no-default-features --features telemetry -- -D warnings, and cargo test --no-default-features --features telemetry (409 tests) all pass.