feat: add distraction counting, timer extensions, and precise breaks

[yashcodes161198]

Pomotroid currently has no way to count distractions during a focus round or extend only the current timer, and the break inputs round durations to whole minutes. This adds those controls while using the existing theme styles.

Changes

• Move remaining time above the dial and add a distraction button inside it. The first click replaces the prompt with 1; subsequent clicks increment the count. The count resets on a new focus round or timer reset and remains visible, but disabled, during breaks.
• Add a +5 button that extends the current focus or break by 300 seconds without changing elapsed time or the running/paused state. Extensions affect the current round only, and session statistics record the extended duration.
• Accept M:SS and decimal minutes in the existing duration inputs, with second-resolution break sliders. For example, 0:15 means 15 seconds and 0:00 skips the break. Keep the one-minute minimum for focus rounds.
• Place the round count and Reset at the bottom left, skip and volume at the bottom right, and Play/Pause below the dial. Remove the backward-style restart button, retaining the existing restart keyboard command.
• Synchronize timing-sensitive engine tests with emitted events instead of assuming a fixed number of ticks after sleeping.

Verification

• Windows: 97 Rust tests passed and the NSIS installer built successfully (build run). The native sources in this PR match that build.
• npm run test:duration: both tests passed.
• npm run check: zero errors and warnings; npm run build passed.
• cargo clippy -- -D warnings passed on Linux in the fork's Build / Test run, using the same native sources.
• Browser checks with mocked Tauri IPC covered distraction counting, keyboard activation, +5 across all round types and running/paused states, duration validation, and five window sizes.

The installer and personal packaging workflow remain in the fork and are excluded from this PR. New strings are supplied in English; other locales use the existing English fallback. Native macOS and Linux interaction has not been manually tested.