Break screen, performance and playback fixes, and an up-to-date README

[alexandre-wayss]

Break screen

When a focus session ends, a full-screen screen shows the break countdown and asks what you'll do in the break: drink water, stretch, rest your eyes, play a game, or anything typed on the spot.

• Activities are editable on the Pomodoro page (new Break screen card): name, hint, icon, which breaks they suit, an optional break length, and an app or link to open when picked.
• The activity done least recently is suggested, so breaks vary; tiles show how many times you did each one today.
• Optional: show it when a break ends too ("5 more minutes" / "Start focus"), keep it up for the whole break, dim other displays, or turn it off in favour of the notification. Both screens can be previewed without touching the timer.
• Return starts the break, Esc closes (the timer keeps running).

Follow-up fixes

• Break screen clicks: it was a non-activating panel, so while another app stayed in front its first clicks (and Return and Escape) were often lost. It now brings Brisa to the front, acts on the first click, and gives focus back to the previous app when it closes. Only its clock redraws every second, and tiles no longer wait to tell a single click from a double-click. Checked on the installed app.
• ⌘Q now quits Brisa, like any Mac app; closing the window keeps it running in the menu bar.

Fixes from the app review

• Imported audio kept in memory is capped at 20 minutes (a long MP3 could decode to several GB), and every sound's loop is prepared off the main thread.
• The per-second countdowns moved out of AppModel, so a running timer only redraws the views that show it; Pomodoro state is no longer written to UserDefaults every second.
• Sleep timer counts down only while playing, fades over the last minute without being undone by the volume slider, and offers the same options everywhere.
• Now Playing names imported sounds; the mini player lists Tones; deleting a mix asks first; a Portuguese label in the English UI is fixed.
• Wake-up routines explain that the Mac must be awake.
• The menu bar icon reopens a closed main window (it didn't open for shared mixes or the break screen's settings link when the window was closed).

Docs

• README rewritten: Pomodoro, break screen, desktop widgets, themes, permissions and privacy, plus a break screen preview.
• ARCHITECTURE.md now lists every source file. Info.plist reports 1.2.0 for local builds.

Testing

• ./Scripts/test.sh: 65 passed (8 new tests for break activities).
• ./Scripts/build.sh and an xcodebuild build of Brisa.xcodeproj both succeed.
• The break screen and the activity editor were rendered offscreen to check the layout; the live window over other apps (typing, Esc, several displays) still needs a manual check via Pomodoro → Break screen → Preview.